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Nickel(II) complexes of azine diphosphine ligands, PR2CH2C(But)NNC(But)CH2PR2 (R=Ph, But, Pri, C6H11), were prepared for the first time by reactions of anhydrous NiX2 (X=Cl, Br, I) with ligands. Complexes are cationic, the counterion being either simple halide anion or, in two cases, 1/2[NiCl4]2−. The azine diphosphines are coordinated terdentately in (E,Z) configuration forming thereby a bicyclic ligand frame (five and six-membered ring) with diphosphine bite angles 160–165°. A balance of stereoelectronic factors governing square planar versus tetrahedral coordination of the ligands is suggested. Structures of four of the complexes with bulky ligands (R=But, X−=Cl−, Br−, I−; R=C6H11, X−=1/2[NiCl]2−) were determined by X-ray diffraction and qualitative Huckel MO calculations on model undistorted square planar [trans-NiX(NH2)(PH3)2]+ were carried out to elucidate the contributions of steric and electronic factors. Two reduction and two oxidation processes depending on the substituent R and the halide were identified from cyclic voltammetry data on the complexes.

Treatment of the phosphino-N-benzoyl hydrazones PPh2CH2C(R)NNHC(O)Ph (R = But, I; R = Ph, II) with [MCl2(NCPh)2] (M = Pd or Pt) gave complexes of type [MCl{PPh2CH2C(But)NNC(Ph)O}] (M = Pd, 1; M = Pt, 2) containing two fused five-membered chelate rings. Metathesis with LiBr or NaI gave [MX{PPh2CH2C(But)NNC(Ph)O}] (X = Br or I; M = Pd or Pt). The complex [PtMe{PPh2CH2C(But)NNC(Ph)O}] (8) was obtained by treating [PtMe2(cod)] (cod = cycloocta-1,5-diene) with one equivalent of I in hot benzene. Treatment of [PtMe2(cod)] with two equivalents of the phosphine II gave [PtMe{PPh2CH2C(Ph)NNC(O)Ph}{PPh2CH2C(Ph)NNHC(O)Ph] (11), containing a six-membered chelate ring and a unidentate coordinated ligand II. Treatment of [PtCl2(NCMe)2] with two equivalents of II in the presence of triethylamine gave [Pt{PPh2CHC(Ph)N–NC(Ph)O}{PPh2CH2C(Ph)NNHC(O)Ph] (12), containing a terdentate (P,N,O-bonded) doubly deprotonated ene-hydrazone ligand and a unidentate ligand II. Prolonged treatment of [PdCl2(NCPh)2] with two equivalents of I in the presence of triethylamine gave [Pd{PPh2CHC(But)NHNC(O)Ph}2] (13), containing two chelated phosphino ene-hydrazide ligands forming six-membered rings. A similar platinum complex, [Pt{PPh2CHC(But)NHNC(O)Ph}2] (14), was synthesised. The terdentate complexes of [MX{PPh2CH2C(But)NNC(Ph)O}] (M = Pd, Pt; X = Cl, Me) underwent base-promoted (NEt3) Michael-type reactions with MeO2CCCCO2Me to give terdentate complexes of the type [MX{PPh2CH[C(CO2Me)CH(CO2Me)]C(But)NNC(Ph)O}] (M = Pd, Pt; X = Cl, Me). The corresponding bromides and iodides were made by metathesis. The crystal structures of 1, 12 and 13 have been determined.

Condensation of 2-pyridylhydrazine, (NC5H4)NHNH2, with the 2-halobenzaldehydes 2,6-dichlorobenzaldehyde, 2-chlorobenzaldehyde or 2-bromobenzaldehyde gave the 2-pyridylhydrazones, (C6H3Cl2-2,6)CHNNH(C5H4N) (1a), (C6H4Cl-2)CHNNH(C5H4N) (1b) or (C6H4Br–2)CHNNH(C5H4N) (1c), respectively. Treatment of 1a with [W(CO)3(NCEt)3] in warm tetrahydrofuran caused oxidative addition of the CCl bond to give the aryl–tungsten(II) complex [W(CO)3Cl{(C6H3Cl-6)CHNNH(C5H4N)C,N,N}] (2a). Similarly, the hydrazones 1b and 1c, when treated with [W(CO)3(NCEt)3], gave the aryl–tungsten(II) complexes [W(CO)3Cl{(C6H4)CHNNH(C5H4N)C,N,N}] (2b) and [W(CO)3Br{(C6H4)CHNNH(C5H4N)C,N,N}] (2c). 1H and 13C–{1H} NMR, IR and mass spectral data are given.

The X-ray crystal structure determination of mer,trans-[RuCl2(PPh3){PPh2CH2C(But)=NN=CH(C6H3F2-2,6)}] (3a) showed the RuF bond distance to be 2.367 A. Treatment of the mixed-azine phosphines Z,E-PPh2CH2C(But)NNCH(C6H4X-2), X=Cl (2c); X=Br (2d); X=I (2e) with the labile Ru(II) complex [RuCl2(PPh3)3] gave chelate complexes mer,trans-[RuCl2(PPh3){PPh2CH2C(But)NNCH(C6H4X-2)], X=Cl (3c); X=Br (3d); X=I (3e) where the halogen atom is interacting with the Ru(II) centre. Elemental analytical, IR, mass and NMR data are given.

Four new ligands of diphosphinoazine type together with their dioxides were synthesized and characterized. The crystal structure of the dioxide Pri 2P(O)CH2C(But)NNC(But)CH2P(O)Pri 2, which crystallizes as a solvate with 1 mol of hydrogen peroxide, was determined by X-ray diffraction. The ligands were used to split the chlorine bridge of bis[μ-chloro-(η3-2-methylpropenyl)palladium], thus forming new binuclear palladium complexes with asymmetric η3-2-methylpropenyl ligand. Phase-sensitive 2D 1H NOESY of the complexes revealed a short distance between syn protons on the terminal carbon of η3-2-methylpropenyl ligand cis to phosphorus and protons of substituent groups on phosphorus for isopropyl, cyclohexyl, and tert-butyl complex. This evidence is further borne out by specifically broad resonances in 13C NMR spectra, suggesting hindered rotation of substituent groups on phosphorus. The diphosphinoazines can be grouped into a series with monotonous change of chemical shifts of selected nuclei (31P, 13C), however, the series is different from that obtained using published substituent contribution data on electron donor–acceptor properties of phosphines.

Novel zero-valent metal complexes [ML2{(Z,Z)-Ph2PCH2C(t-Bu)=N-N=C(t-Bu)CH2PPh2}] (M = Ni, L = CO, t-BuNC) with the azine diphosphine chelating in a nine-membered ring were prepared. The nickel dicarbonyl complex was found to be in an equilibrium with its isomer containing (E,Z)-chelated azine diphosphine, the equilibrium being on the side of the (Z,Z)-isomer below 60 °C. A similar palladium complex (M = Pd, L2 = CH3OCOC≡CCOOCH3) prepared earlier was found to undergo a rearrangement with simultaneous alkyne-to-alkenyl conversion of the acetylenedicarboxylate dimethyl ester ligand.

Treatment of the phosphino N , N -dimethylhydrazone Z -PPh 2 CH 2 C(Bu t )NNMe 2 ( 1 ) with [RuCl 2 (CO) 2 ] x gave th dichlorocarbonyl-ruthenium(II) complex cis , cis -[RuCl 2 (CO) 2 {PPh 2 CH 2 C(Bu t )NNMe 2 }] ( 4 ). Treatment of the phosphino hydrazone Z -PPh 2 CH 2 C-(Bu t )NNH 2 ( 2 ) with [RuCl 2 (CO) 2 ] x gave the chloromonocarbonylruthenium(II) complex salt [RuCl(CO) {PPh 2 CH 2 C-(Bu t )NNH 2 } 2 ]Cl ( 5 ). Treatment of the azine diphosphine Z , Z -PPh 2 CH 2 C(Bu t NNC(Bu t CH 2 PPh 2 ( 3 ) with [RuCl 2 (CO) 2 ] x gave the dichlorocarbonylruthenium(II) complexes fac , cis -[RuCl 2 (CO) {PPh 2 CH 2 C(Bu t )NN C(Bu t )CH 2 PPh 2 }] ( 6 ) and mer , cis -[RuCl 2 (CO){PPh 2 CH 2 C(Bu t )NNC(Bu t ) CH 2 PPh 2 }] ( 7 ), which were easily separated. Irradiation of 7 in chloroform solution with a mercury arc lamp yielded 6 quantitatively. When a solution of 6 in 2-methoxyethanol was put aside at 20°C in daylight, it rearranged to 7 with mer , trans -[RuCl 2 (CO){PPh 2 CH 2 C(Bu t )NNC(Bu t )CH 2 PPh 2 }] ( 8 ).

Condensation of Z-PPh 2 CH 2 C(Bu t )=NNH 2 with 4-nitroacetophenone gave the azine phosphine Z,E -PPh 2 CH 2 C(Bu t )=N-N=CMe(C 6 H 4 NO 2 -4) ( I ). The corresponding phsophine oxide II was prepared by treatment of I with H 2 O 2 . The phosphine I with [Mo(CO) 4 (nbd)] (nbd=norbornadiene) gave [Mo(CO) 4 {PPh 2 CH 2 C(Bu t )=N-N=CMe(C 6 H 4 NO 2 -4)}] ( 1a ); the corresponding tungsten 1b and chromium 1c complexes were made similarly. The crystal structure of 1a was determined by X-ray diffraction and showed the presence of a six-membered chelate ring with the bulky 4-nitrophenyl group held close to the metal. Oxidation of 1a with bromine gave the seven-coordinate molybdenum (II) complex 2 . Treatment of [PtMe 2 (cod)] (cod=cycloocta-1,5-diene) with I at 20°C gave the dimethyl-platinum (II) complex [PtMe 2 {PPh 2 CH 2 C(Bu t )=N-N=CMe(C 6 H 4 NO 2 -4)}] ( 3a ) which with MeI gave the iodotrimethylplatinum(IV) complex 4 . Treatment of 3a with C≡O opened the chelate ring to give the dimethyl(carbonyl)platinum(II) complex 5 containing a monodentate phosphine ligand. When 3a was heated in toluene solution at 110°C it gave the cyclometallated methylplatinum(II) complex [PtMe{PPh 2 CH 2 C(Bu t )=N-N=CMe(C 6 H 3 NO 2 -4)}] ( 6 ). Treatment of 6 with MeI gave the platinum(IV) complex 7 . The dichloropalladium(II) complex [PdCl 2 {PPh 2 CH 2 C(Bu t )=N-N=CMe(C 6 H 4 NO 2 -4)}] ( 3b ) was prepared by treatment of [PdCl 2 (NCPh) 2 ] with I in CH 2 Cl 2 . Treatment of [PtCl 2 (NCMe) 2 ] with 2 equiv. of I gave the trans -bis(phosphine) complex 8 . When 2 equiv. of I were treated with [PtCl 2 (cod)] followed by NH 4 PF 6 this gave the salt 9a containing two six-membered chelate rings; the analogous palladium(II) 9b) salt was also prepared. Treatment of 2 equiv. of I with [PtCl 2 (cod)] followed by NH 4 PF 6 gave the PF 6 salt 10 containing a six-membered chelate ring and a monodentate ligand. When 10 was treated with AgNO 3 followed by NH 4 PF 6 this gave the bis-chelate complex 11 containing five- and six-membered chelate rings. Treatment of [IrCl(CO) 2 ( p -toluidine)] with I gave the cyclometallated iridium(III) hydride complex [IrHClCO{PPh 2 CH 2 C(Bu t )=N-N=CMe(C 6 H 3 NO 2 -4)}] ( 12 ). [RuCl 2 (PPh 3 ) 3 ] with the phosphine I resulted in the Ru(II) complex 13 in which the ortho hydrogens of the 4-nitrophenyl group are agostically interacting with ruthenium. Proton, Phosphorus-31, some carbon-13 NMR and IR data have been obtained. Crystals of 1a are orthorhombic, space group Pna 2 1 , with a = 1819.3(2), b = 1050.0(1), c = 1614.8(2) pm and Z = 4; final R = 0.0191 for 2616 observed reflections.

Treatment of the azine diphosphine Z,Z-PPh2CH2C(But)N–NC(But)CH2PPh2 I with [IrCl(CO)2(H2NC6H4Me-4)] in benzene gave the ene–hydrazone diphosphine iridium(III) hydride [IrH(Cl)(CO){PPh2CHC(But)N–NC(But)CH2PPh2}], 1, which isomerised reversibly to the ionic square planar iridium(I) complex [Ir(CO){PPh2CH2C(But)N–NC(But)CH2PPh2}]Cl 2a, containing an azine diphosphine. Treatment of 1 with NEt3 gave the neutral ene–hydrazone diphosphine iridium(I) complex [Ir(CO){PPh2CHC(But)N–NC(But)CH2PPh2}] 3 which is reactive and undergoes oxidative addition of H2 to give the iridium(III) dihydride mer,cis-[IrH2(CO){PPh2CH C(But)N–NC(But)CH2PPh2}] 4 and oxidative addition of MeI to give the methyliridium(III) complex [IrMe(I)(CO){PPh2CHC(But)N–NC(But)CH2PPh2}] 5. It reacted rapidly with olefins or acetylenes (L), i.e.N-methylmaleimide, ethene or dimethyl acetylenedicarboxylate, to give the five-co-ordinate adducts [Ir(CO)L{PPh2CH C(But)N–NC(But)CH2PPh2}], 6a, 6b or 6c, respectively, also with O2 to give the η2-dioxygen adduct [Ir(CO)(η2-O2){PPh2CHC(But)N–NC(But)CH2PPh2}] 7. Treatment of 3 with 1 mol of picric acid protonated the ene–hydrazone diphosphine backbone to give the azine diphosphine iridium(I) salt [Ir(CO){PPh2CH2C(But)N–N C(But)CH2PPh2}][OC6H2(NO2)3] 2b. The N-methylmaleimide adduct 6a was similarly protonated to give the corresponding azine diphosphine iridium(I) salt [Ir(CO)(η2-COCHCHCONMe){PPh2CH2C(But)N–NC(But)CH2PPh2}][OC6H2(NO2)3] 8. Complex 1 was protonated by HCl to give the corresponding azine diphosphine iridium(III) salt [IrH(Cl)(CO){PPh2CH2C(But)N–NC(But)CH2PPh2}]Cl 9a, which is converted into 3 when treated with NEt3. The 1H, 13C and 31P NMR and some IR data are given.

Treatment of (1R)-(+)-camphor azine with 2 mole equivalents of butyllithium, followed by chlorodiphenylphosphine, gave the azine diphosphines Z,Z-3,3′-Ph2PnC10H15N–NC10H15PxPh2 I and Z,Z-3,3′-Ph2PxC10H15 N–NC10H15PxPh2 II (x = exo, n = endo); the structures of these were determined by X-ray diffraction. On boiling an ethanol solution of the exo,exo-diphosphine II with sodium ethoxide or a propan-2-ol solution containing hydrazine hydrate and acetic acid the diphosphine isomerised to the corresponding exo,endo-diphosphine I. The corresponding diphosphine dioxides III and IV were prepared by treating I or II with H2O2, respectively. Treatment of I with [Mo(CO)4(nbd)] (nbd = norbornadiene) or with [Mo(CO)3(cht)] (cht = cyclohepta-1,3,5-triene) gave fac-[Mo(CO)3(Ph2PnC10H15N–NC10H15PxPh2)] 1a. Treatment of I with [W(CO)4(nbd)] gave the tricarbonyltungsten(>0>) complex fac-[W(CO)3(Ph2PnC10H15N–NC10H15PxPh2)] 1b and the analogous mer complex mer-[W(CO)3(Ph2PnC10H15N–NC10H15PxPh2)] 2. Treatment of II with [W(CO)6] gave the mer,exo,endo tricarbonyl complex 2, and the fac,endo,endo complex fac-[W(CO)3(Ph2PnC10H15N–NC10H15PnPh2)] 3. Treatment of II with [M(CO)4(nbd)] (M = Mo, W or Cr) gave mainly a complex of type fac-[M(CO)3(Ph2PxC10H15N–N C10H15PxPh2)] (M = Mo 4a, W 4b or Cr 4c). The crystal structure of the tricarbonyltungsten(>0>) complex 4b was determined by X-ray diffraction and the chirality around tungsten shown to be C, i.e. clockwise. Treatment of 4b with 1 mole equivalent of bromine gave the tricarbonyltungsten(II) bromide salt [WBr(CO)3(Ph2PxC10H15N–N C10H15PxPh2)]Br 5. Infrared, proton, phosphorus-31 and some carbon-13 NMR data are given.

Treatment of the neutral chloropalladium(II) complexes [PdCl{PPh 2 CHC(R)–N–NC(R)+ + CH 2 PPh 2 }] (R = Bu t 1a or Ph 1b) with two equivalents of Li[N(SiMe 3 ) 2 ] gave the novel dipalladium(II) complexes [{Pd[PPh 2 CHC(R)–N–NC(R) CHPPh 2 ]} 2 ] (R = Bu t 2a or Ph 2b) containing two palladium–carbon bonds, five fused chelate rings and enamine type (CC–N) moieties. Treatment of the chloroplatinum(II) complex [PtCl{PPh 2 CHC(Bu t )–N–+ + NC(Bu t )CH 2 PPh 2 }] 1c with an excess of KOBu t in dimethyl sulfoxide (dmso) gave what was probably the species [Pt{PPh 2 CHC(Bu t )–N–N C(Bu t )CHPPh 2 }(dmso)] 3 containing both a co-ordinated and an unco-ordinated phosphine. The dipalladium(II) complex 2a or 2b underwent electrophilic attack at the enamine carbon with acids (HX) to give salts of type [{Pd[PPh 2 CH 2 C(R)N–NC+ + (R)CHPPh 2 ]} 2 ]X 2 4 (R = Bu t or Ph; X = trifluoroacetate, chloride or picrate); these, when treated with sodium methoxide, deprotonated at the methylene carbon to give the neutral complex 2a or 2b. Treatment of 2a with less than 2 equivalents of trifluoroacetic acid gave the monoprotonated complex [Pd{PPh 2 CHC(Bu t )N–NC+ + (Bu t )CHPPh 2 }{PPh 2 CH 2 C(Bu t )N–NC(Bu t ) CHPPh 2 }][O 2 CCF 3 ] 5a, mixed with 2a and 4a. Complex 2a with Br 2 or MeI underwent attack at the enamine carbon CC–N to give the corresponding bromo or methyl derivatives [{Pd[PPh 2 CH(R)CBu t N–N C(Bu t )CHPPh 2 ]} 2 ]X 2 (R = Br, X = Br 6a; R = Me, X = I 6b) respectively. When the methyl-substituted salt was treated with KOBu t it gave the neutral dipalladium(II) complex [{PdCl[PPh 2 C(Me) C(Bu t )–N–NC(Bu t )CHPPh + + 2 ]} 2 ] 7. The crystal structure of 2a was determined.

Treatment of the phosphino-N,N-dimethylhydrazone Z-PPh 2 CH 2 C(Bu t )NNMe 2 with benzohydrazide in the presence of acetic acid gave the phosphino-N-benzoylhydrazone PPh 2 CH 2 C(Bu t )NNHC(O)Ph I. Treatment of the phosphine I with 0.5 equivalent of [{RhCl(CO) 2 } 2 ] gave the rhodium(I) complex [Rh(CO){PPh 2 CH 2 C(Bu t )N–NC(Ph)O}] 1 containing two fused five-membered chelate rings. Complex 1 readily reacted with Br 2 to give the dibromorhodium(III) complex [RhBr 2 (CO){PPh 2 CH 2 C(Bu t )N–NC(Ph) O }] 2. Similarly, it underwent oxidative-addition reactions with MeI or HCCCH 2 Cl to give rhodium(III) complexes of type [RhX(R)(CO){ PPh 2 CH 2 C(Bu t ) N–NC(Ph) O }] (R = Me, X = I 3; R = CHCCH 2 , X = Cl 4). In contrast, treatment of 1 with allyl bromide caused loss of the carbon monoxide ligand to give the η 3 -allylrhodium(III) complex [RhBr(η-3-C 3 H 5 ){ PPh 2 CH 2 C(Bu t ) N–NC(Ph)O }] 5. Treatment of 1 with MeO 2 CCCCO 2 Me gave the cyclometallated alkenylrhodium(III) complex [Rh(CO){C(CO 2 Me)CHCO 2 Me }{ PPh 2 CH[C(CO 2 Me) C(CO 2 Me)]C(Bu t ) N–NC(Ph)O }] 6, in which the phosphine ligand is tetradentate through P, N, O and C; in the formation of 6 one alkyne has attacked the methylene carbon of the phosphine ligand and the second has added to Rh–H to give RhC(CO 2 Me)CH(CO 2 Me). On the prolonged heating 6 isomerised to give the rhodium(III) complex 7; in this isomer the C(CO 2 Me)CH(CO 2 Me) ligand is trans to phosphorus whereas in 6 it is cis. The crystal structure of 6 has been determined.

Complexes of gold, silver and copper with the azine diphosphine Z,Z-PPh 2 CH 2 CBu t N–NC(Bu t )CH 2 PPh 2 have been prepared and shown to contain the diphosphine in an unusual nine-membered chelate ring; the crystal structure of the chlorogold derivative [AuCl{Z,Z-PPh 2 CH 2 CBu t N–NC(Bu t )CH 2 PPh 2 }] was determined.

tert-Butyl diphenylphosphinomethyl ketone N-phenylhydrazone, Z-PPh,CH$ (Bu’) =NNHPh ( l), was prepared by heating the phosphino NJ-dimethylhydrazone, Z-PPh$JH&( Bu’) =NNMe, with PhNHNHP in ethanol in the presence of acetic acid as catalyst. This phosphine was converted into the corresponding phosphine oxide 2a and phosphine sulfide 2b. Treatment of [ Mo( CO),( nbd) ] (nbd = norbomadiene) with 1 equiv. of 1 gave the tetracarbonylmolybdenum(0) complex [Mo(CO),{PPhH [ Mo(CO),( nbd) ] with 2 equiv. of 1 gave the bis(phosphine)molybdenum( 0) complex cis-[ Mo( C0)4(PPh2CH2C( Bu’)=NNHPh),] (4) in which 1 is monodentate through P. Treatment of [ PdCll( NCPh)2] or [ PtCl,( cod) ] (cod = cycloocta-1,5-diene) with 2 equiv. of 1 gave the complexes cis- [ MC12( PPh2CH2C( Bu’)=NNHPh}J (M = Pd (5a). R (5b) ). The crystal structure of 5a was determined. Treatment of [ PtC12( NCMe),] with 2 equiv. of the phosphine 1 gave trans- [ PtClz( PPh2CH2C( Bu’) =NNHPh),] (5~). Dehydrochlorination of the platinum( II) dichloride 5b or 5c with Et,N gave the neutral cis- [ Pt{ PPh2CH2C( Bu’) =NNPh},] (6)) containing two six-membered chelate rings. Treatment of the T-2-methylallyl complex [ [ ( T3-2-MeC3H4)PdCl),] with 2 equiv. of the phosphine 1 gave the neutral complex [ ( v32-MeC,H,)PdCl(PPh,CH,C(Bu’)=NNHPh}] (7) in which 1 is monodentate through P. Dehydrochlorination of 7 with aqueous NaOH solution gave the r-methylallylpalladium( II) chelate complex [ ( $-2-MeC,H.,)Pd( PPh2CH2C( Bu’) =NNPh) ] (8) containing an amidepalladium bond. Treatment of 1 with LiBu” followed by PPh*Cl gave the diphosphine Z-PPh$H$(Bu’)=NN(Ph)PPh, (9) which with 0.5 equiv. of [ { ( ~3-2-MeC3H,)PdC1)2] followed by NH.,PF, gave the r-methylallylpalladium(II) PF, salt [ ( q3-2-MeC3H4)Pd(PPh&H&( Bu’)rNN(Ph)PPh,) ]PF, (10). Crystals of 5a are monoclinic, space group P2,/c, with a = 12.900( 2)) b = 40.083( 6), c== 10.8779( 11) A, p= 111.891(7)” and Z=4, final R=0.0535 for 7558 observed reflections with F>4.0~( F).

Treatment of the azine diphosphine Z~Z--PPh2CH2C (But ) --N-N=C(But) CH2PPh2 (1) with 0.5 equiv, of [ { ( r/3-2-MeCaH4)PdCI }2] gave the cationic palladium (II) complex [ (~-2-MeC3H4) Pd { PPh2CH2C (But ) =N-N=C (Bu t) CH2PPh2 } ] CI (2a), containing a nine-membered chelate ring with the azine in the E,Z-configuration. The crystal structure of 2a shows that the E,Z-azine backbone C--C=N-N=C--C is essentially planar and the methylallyl ligand is non-planar. The corresponding PF6 salt 2b was prepared using NH4PF 6 in EtOH. The proton NMR spectra of 2b were temperature dependent, and at 243 K the slow exchange limiting spectrum was obtained in which all four CH2P protons were inequivalent, as were the four allylic protons with 4J(H~,H,r,) 22.2 Hz. Proton, 31p{IH} and 13C{IH} NMR data are given. Crystals of 2a are monoclinic, space group P21/n with a= 10.3449(8), b-- 18.457(2), c=21.705(2) ,~, t= 101.140(7)* and Z=4, RI = 0.0495 for 5769 observed reflections with I> 2.0 tr(l).

Treatment of [IrCl(CO)2(H2NC6H4Me-p)] with the azine diphosphine PPh2CH2(But)N–NC(But)CH2PPh21 in benzene gave the co-ordinatively saturated (18e) octahedral iridium(III) hydride [IrH(Cl)(CO)(PPh2CHC(But)–N–NC(But)CH2PPh2}]3 in which the P,N,P-terdentate diphosphine ligand had lost a hydrogen to give an ene–hydrazone backbone. On dissolution in methanol or ethanol, complex 3 immediately dissolved to give the isomeric but co-ordinatively unsaturated (16e) iridium(I) complex [Ir(CO){PPh2CH2C(But)N–NC(But)CH2PPh2}]Cl 4a in which the P,N,P-terdentate ligand backbone contained an azine moiety. Complex 4a was readily converted to the corresponding PF6 salt 4b. On dissolution in dichloromethane or benzene 4a rapidly gave back 3. Treatment of 4b with acetylenes or olefins gave adducts [Ir(CO){PPh2CH2C(But)N–NC(But)CH2PPh2}L]PF6 in which L = MeO2CCCCO2Me 5a, HCCCO2Me 5b, MeN(OC)CHCHCO 8a, trans-MeO2CCHCHCO2Me 8b, trans-EtO2CCHCHCO2Et 8c, C2H48d or CH2CCH28e,8f. Proton NMR studies on the ethene adduct showed that the ethene ligand was rotating at ca. 20 °C but at –40 °C rotation had stopped. Allene gives a mixture of two isomeric adducts 8e and 8f. Complex 4b reacted with PhCCH in a different fashion to give the phenylacetylide hydride fac-[IrH(CCPh)(CO){PPh2CH2C(But)N–NC(Bu)t)CH2PPh2}]PF66 which isomerised on heating to mer-[IrH(CCPh)(CO){PPh2CH2C(But)N–NC(But)CH2PPh2}]PF67. Treatment of 4b with EtO2CNNCO2Et gave an adduct [Ir(CO){PPh2CHC(But)–N–NC(But)CH2PPh2}(EtO2CNHNCO2Et)]PF69 in which the diphosphine backbone had been deprotonated and the diethyl azocarboxylate protonated. Treatment of 4b with carbon monoxide gave the dicarbonyliridium complex [Ir(CO)2{PPh2CH2C(But)N–NC(But)CH2PPh2}]PF610. Treatment of 4b with dihydrogen gave a dihydridoiridium(III) adduct 11 in which the terdentate P,N,P diphosphine was in the fac arrangement. In solution 11 slowly isomerised over several hours to give a dihydride in which the terdentate P,N,P diphosphine was in the mer arrangement, i.e. the structure of the dihydride was 12. Complex 4b underwent other types of oxidative-addition reactions, i.e. with formic acid it gave the hydride mer-[IrH(O2CH)(CO){PPh2CH2C(But)N–NC(But)CH2PPh2}]PF613, with methyl iodide the mer-methyliridium(III) adduct 14 and with bromine the mer-iridium(III) dibromide 15. The crystal structures of 5a and 8a were determined.

Deprotonation of 4-tert-butyl-cyclohexanone N,N-dimethylhydrazone (1) with LiBu n at - 15 °C, followed by addition of PPh2CI gave the corresponding phosphino dimethylhydrazone Z-PPh2CtoHtT=NNMe2 (2), in which the PPh2 group is in the axial position. 2 reacts with [Mo(CO)4(nbd) ] (nbd= norbomadiene) to give the tetracarbonyl complex [Mo(CO)4(Z-PPh2CtoH~7=NNMe2)] (3), containing a sixmembered chelate ring and an axial PPh2 group. Treatment of 2 with Na2PdCI4 or [ PdCI2 (NCPh)2] gave the dichloropailadium (II) complex [PdCI2(E-PPh2C~oH~7=NNMe2) ] (4), containing a five-membered chelate ring and an equatorial PPh2 group due to isomerisations at C 2 and around C--N. Crystals of 3 are monoelinic, space group P2~/n with a = 2083.4(4), b = 1089.0(2), c = 2521.9(5) pm, t= 98.82(2) ° and Z=8, R=0.0263 for 6109 observed reflections with l>2.0~r(/). Crystals of 4 are monoclinic, space group P2~/n with a= 11.271(2), b = 13.205(3), c = 17.849(3) A, t= 104.83( 1)° and Z= 4, R~ = 0.0304 for 3994 observed reflections.

Treatment of Z-PPh2CH2C(But)=NNH2 with 4-methylphenylthiomethyl methyl ketone gave the thioether azine phosphine Z,E-PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4) 1, which with H2O2 gave the corresponding phosphine oxide 2. Treatment of 1 with [Mo(CO)3(η6-cht)] or [W(CO)3(NCEt)3] gave the yellow tricarbonyl complexes fac-[M(CO)3{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}] 3a (Mo) or 3b (W), respectively. Treatment of 1 with [Mo(CO)4(nbd)] gave the pale yellow tetracarbonylmolbdenum(0) complex [Mo(CO)4{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}] 4, in which the ligand 1 is bidentate through P and N. Oxidation of either 3a or 4 with 1 equivalent of bromine gave the orange neutral seven-coordinate dicarbonylmolybdenum(II) complex [MoBr2(CO)2{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}] 5, whereas the tungsten complex 3b with 1 equivalent of bromine gave the seven-coordinate tricarbonyltungsten(II) cation [WBr(CO)3{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}]+ isolated as the PF6 salt 6. Treatment of 1 with [PtCl2(NCMe)2]gave the yellow dichloroplatinum(II) complex [PtCl2{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}] 7, in which 1 is bidentate through P and N. When 7 was treated with NH4PF6 in methanol it gave the terdentate salt [PtCl{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}]PF68a. Deprotonation of 7 with NEt3-NaOH gave the orange neutral chloroplatinum(II) complex [PtCl{PPh2-CH2C(But)N-NC(Me)=CHS(C6H4Me-4)}] 9, containing a terdentate ene-hydrazone phosphine ligand. This neutral complex 9 was reprotonated using HBF4 to give the BF4 salt 8b. Treatment of the phosphine 1 with [PtMe2(cod)] gave the white dimethylplatinum(II) complex [PtMe2{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}] 10, containing the bidentate azine ligand. Treatment of 10 with MeI gave the white platinum(IV) iodide salt fac-[PtMe3{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}]I 11a in which the azine is terdentate. When 11a was treated with NH4PF6 in MeOH the PF6 salt 11b was obtained. Treatment of 10 with picric acid gave the yellow methylplatinum(II) picrate salt [PtMe{PPh2CH2C(But)=N-N=C(Me)CH2S(C6H4Me-4)}][OC6H2(NO2)3-2,4,6] 12 and methane. Infrared, 31P–[1H], 1H, and some 13C–[1H] NMRdata are given. Keywords: azine phosphine, thioether, metal-carbonyls, platinum.

Air oxidation of the tricarbonylmolybdenum(II) complex [ MoCl 2 ( CO 2 ( PPh 2 C 10 H 15 = NH )] ( 20 ) gave the oxygen oxomolybdenum(V) complex [{ MO (= O ) Cl 2 ( O = PPh 2 C 10 H 15 = NH )} 2 O ] ( 4 ) , containing bidentate imino-phosphine oxide ligands. Crystals of (4) are orthorhobic, space group P21P212121 with a = 13.885(2), b = 18.308(4), c = 18.439(5) A , Z = 4, R = 0.0395 for 3531 observed reflections with I > 2.0σ(I). Each molybdenum atom is in a disorted octahedral coordination linked by a bent Mo-O-Mo bridge with an angle of 158.2(3)°, and Mo(=O) groups are cis to each other.

Condensation of Z -PPh 2 CH 2 (Bu t ) = NNH 2 ( 1 ) with pentofluorobenzaldehyde gave the azine phosphine Z , E -PPh 2 CH 2 C(Bu t )NNCH(C 6 F 5 ) When 2 was heated in benzene with [IrCl(CO) 2 ( p -toluidine)], it gave the cyclometallated dichlorocarbonyliridium(III) complex [IrCl 2 (CO){PPh 2 CH 2 C(Bu t NCH(C 6 F 4 )}] ( 4 ), the formation of which involved a CF bond fission. Proton, 31 P{ 1 H}, 13 C{ 1 H} and 19 F NMR data are given. Crystals of 4 are monoclinic, space group P 2 1 / c with a = 10.6313(11), b = 16.0243(14), c = 17.968(2) A, β=100.258(7)° and Z = 4, R 1 = 0.0299 for 6085 observed reflections with I > 2.0 σ ( I ).

Mixed monoazines of types H2CN–NC10H16[C10H16 is a (1R)-(+)-camphor residue (L1), or a (1R)-(–)-fenchone residue (L2)] or Me2CN–NC10H16[C10H16 is a (1R)-(+)-camphor residue (L3)], or α-diazines C10H16N–NCH–CHN–NC10H16[C10H16 is a (1R)-(+)-camphor residue (L4) or a (1R)-(–)-fenchone residue (L5)], or α-2-pyridyl azines C10H16N–NCHC5H4N [C10H16 is a (1R)-(+)-camphor residue (L6) or a (1R)-(–)-fenchone residue (L7)] reacted with Na2PdCl4 to give compounds of type [PdCl2Ln2] for L1, L2 or L3 as monodentate nitrogen-donor ligands and chelated mononuclear complexes of the type [PdCl2Ln] for L4, L5, L6 or L7. The complexes of the monodentate azines L1 and L2 exist in solution as mixtures of isomers differing in the ligating nitrogens. The compounds L1, L2 and L4–L7 also reacted with [Pd2Cl4(PR3)2] to give [PdCl2(PR3)Ln](n= 1, R3= Me2Ph or Me2(C6H4OMe-4); n= 2, R3= Me2Ph, Me2(C6H4OMe-4) or Ph3; n= 4 or 5, R3= Me2Ph; n= 6, R3= Bun3; n= 7, R3= Bun3 or Me2Ph), in which the ligands are monodentate, or [{PdCl2(PR3)}2Ln](Ln= L4–L7, R3= Me2Ph), in which the ligands are bidentate bridging. The phosphine complexes were characterised in solution but were isolated only for [PdCl2(PR3)Ln](Ln= L6, R3= Bun3; L7, R3= Bun3 or Me2Ph; L2, R3= Ph3). Compounds L4, L6 or L7 reacted with the η3-methylallylpalladium complex [{PdCl(η3-CH2CMeCH2)}2] and NH4PF6 to give [Pd(η3-CH2CMeCH2)Ln] PF6(Ln= L4, L6 or L7). The crystal structure of [PdCl2L6]·0.5CH2Cl2 was determined by X-ray diffraction analysis: the crystals are monoclinic, space group P21 with a= 9.5830(13), b= 13.9720(14) and c= 14.726(2)A, β= 97.610(11)° and Z= 4. It shows two molecules of the complex in the asymmetric unit differing only in the torsion angles around the N–N bond.

The phosphino hydrazone Z-PPh,CH,C(Bu’)=NNH, (1) condenses with 2,6-difluorobenzaldehyde to give Z, EPPh,CH,C(Bu’)=N-N=CH(C&F,-2,6) @a), which reacts rapidly with the labile ruthenium(I1) complex [RuC&(PPh,),] to give mer,trans-[RuC1,(PPh,){PPh,CH,C(Bu’)=N-N=CH(CsH3Fz-2,6)] (3a). In the “F{‘H} NMR spectrum of 3a the fluorines are coupled equally to PA but are not coupled to Pa. In the 3’P{1H} NMR spectrum, P, is coupled equally to both fluorines, i.e. there is a dynamic system with both fluorines coordinated to ruthenium in turn and coupled to P,, ‘J(P,F) =68 Hz. Similar condensations of 1 with other fluorine-substituted benzaldehydes, viz. pentafluorobenzaldehyde, 2-chloro-6-fluorobenzaldehyde, 2_fluorobenzaldehyde, 2,3-difluorobenzaldehyde, gave mixed azine phosphines. In each case these mixed azine phosphines when treated with [RuC&(PPh&], displaced two triphenylphosphines to give terdentate chelates showing fluorine coordination to ruthenium. Proton, 3’P{1Hj and 19F{‘H} NMR data are given and discussed.

The phosphino hydrazone Z-PPh2CH2C(But)NNH2I has been shown to be a convenient ‘reagent’ for converting aldehydes or ketones into azines which can then be cycloiridated rapidly with C–H bond fission to give iridium(III) hydrides. Condensation of I with a series of substituted benzaldehydes (RCHO) gave mixed azines of type Z,E-PPh2CH2C(But)N–NCHR [R = C6H2(OMe)3-3,4,5 IIa, Ph IIb, C6H4OMe-4 IIc, C6H4NO2-4 IId, C6H4Br-2 IIe, C6H4Cl-2 IIf, C6H4F-2 IIg, C6H4OH-2 IIh or C6H2(OH-2)(OMe)2-4,6, IIi]. The Z,E configuration is necessary for the subsequent cyclometallation and when the azine IIa was treated with [IrCl(CO)2(H2NC6H4Me-p)] in benzene at 75 °C for 5 min it underwent an aryl C–H bond fission to give the cyclometallated chlorocarbonyliridium(III) hydride [[graphic omitted]H(OMe)3-3,4,5]}]1a. The crystal structure of 1a showed that (i) oxidative addition of the aryl C–H bond to iridium was cis with the hydride ligand trans to chloride, and (II) the cyclometallated azine ligand was in the terdentate mer arrangement. Azines IIb–IIg reacted similarly. Treatment of IIh with [IrCl(CO)2(H2NC6H4Me-p)] in dichloromethane at 20 °C effected O–H bond fission to give the O-cyclometallated iridium(III) hydride [[graphic omitted])}], which isomerised in benzene at 75 °C to the C-metallated isomer. Similar treatment of IIi also gave an O-cyclometallated iridium(III) hydride. The phosphino hydrazone I condensed with ferrocenecarbaldehyde to give an azine, which with [IrCl(CO)2(H2NC6H4Me-p)] gave a cyclometallated iridium(III) hydride. Treatment of I with the 2-carbaldehydes of pyrrole, N-methylpyrrole or thiophene or with indole-3-carbaldehyde gave the corresponding azine phosphines with the required Z,E configuration. When the pyrrole azine was treated with [IrCl(CO)2(H2NC6H4Me-p)] the N-cyclometallated chlorocarbonyliridium(III) hydride [[graphic omitted])}] was formed via a N–H bond fission. The azine phosphines of N-methylpyrrole, thiophene and indole gave C-cyclometallated chlorocarbonyliridium(III) hydrides. Condensation of I with cinnamaldehyde or 3-methylpent-3-en-2-one gave azines which underwent oxidative addition of the olefinic C–H bonds readily to give corresponding C-cyclometallated iridium(III) hydrides. Phosphino hydrazone I also condensed with tert-butyl methyl ketone to give an azine which with [IrCl(CO)2(H2NC6H4Me-p)] gave the C-cyclometallated chlorocarbonyliridium(III) hydride, i.e. metallation in this case occurred on the single methyl group. Proton, 31P-{1H} and some 13C-{1H} NMR data are given.

Treatment of the tricarbonylmolybdenum(0) complex, [[graphic omitted]·Ph2}]1a with 1 equivalent of LiBun selectively deprotonated the backbone to give the carbanion [[graphic omitted]Ph2}]–, which on addition of methyl iodide or allyl bromide gave the monoalkyl complexes [[graphic omitted]Ph2}](R = Me 2a or CH2CHCH23a). The tungsten(0) analogues 2b and 3b were similarly prepared from [[graphic omitted]Ph2}]1b. Treatment of the tricarbonyltungsten(0) carbanion with deuterium oxide gave the monodeuteriated complex [[graphic omitted]Ph2}]4. Treatment of 1b with 4 equivalents of LiBun followed by methyl iodide gave the dimethyl complex [[graphic omitted]Ph2}]5a, specifically as R,R and S,S isomers. Complex 5a was also prepared by deprotonating and methylating 2b. The analogous molybdenum complex 5b was similarly prepared from 1a. Proton, 13C-{1H}, 31P-{1H} NMR and infrared data are reported. The crystal structures of 2a and 5a have been determined.

tert-Butyl diphenylphosphinomethyl ketone hydrazone, Z-PPh2CH2C(But)NNH2 condensed with 2–acetylpyridine to give Z,E-PPh2CH2(But)CN–NC(Me)C5H4N la, which reacts with [M(CO)4(nbd)](nbd = norbornadiene) to give highly coloured tricarbonyl complexes [[graphic omitted]}](M = Mo 1a, W 1b or Cr 1c). Under mild conditions, la reacted with [PtMe2(cod)](cod = cycloocta-1,5-diene) to give the dimethylplatinum(II) complex [[graphic omitted]C(Me)C5H4N}]2 containing the bidentate azine phosphine ligand. Complex 2 reacted with Mel to give the fac-trimethylplatinum(IV) iodide salt [[graphic omitted]}]3 in which the phosphine is terdentate. Under slightly acidic conditions, la reacted with [PtMe2(cod)] to give a yellow methylplatinum(II) cation isolated as the PF6 salt, [[graphic omitted]}]PF64a. Deprotonation of this cation with NaOMe gave the deep blue neutral methylplatinum(II) complex [[graphic omitted]}]5a, containing a terdentate azo phosphine ligand. Treatment of [PtCl2(cod)] with la gave the yellow chloride salt [[graphic omitted]}]Cl 4b, which with NH4PF6 gives the corresponding PF6 salt 4c. Sodium methoxide immediately deprotonates 4b to give the intensely deep blue neutral chloroplatinum(II) complex [[graphic omitted]}]5b. Treatment of [PdCl2(NCPh)2] with la gave the yellow chloropalladium(II) chloride salt [[graphic omitted]}]Cl 4d, which on deprotonation with NEt3, gives the deep purple, neutral chloropalladium(II) complex 5c. Infrared, 31P-{1H}, 1H, some 13C-{1H} NMR and UV/VIS data are given.

Treatment of [RuCl2(PPh3)3]2 with the azine phosphine Z,E-PPh2CH2C(But)N–NC(Me)But3a, derived from MeC(O)But, gave the δ-agostic tert-butyl complex mer,trans-[RuCl2(PPh3){PPh2CH2C(But)N–NC(Me)But}]4a, in which all nine hydrogens of the tert-butyl group are agostically interacting with ruthenium on the NMR time-scale at 20°C. The analogous δ-agostic tert-butyl complex mer,trans-[RuCl2(PPh3){PPh2CH2C(But)N–NC(H)But}]4b was also prepared. Treatment of 2 with the symmetrical azine diphosphine Z,Z-PPh2CH2C(But)N–NC(But)CH2PPh25 gave the δ-agostic tert-butyl complex mer,trans-[RuCl2(PPh3){PPh2CH2C(But)N–NC(But)CH2PPh2}]6, in which one of the PPh2 groups is unco-ordinated. Treatment of 2 with the azine phosphine Z,E-PPh2CH2C(But)N–NC10H167, derived from pinacolone–fenchone mixed azine, gave the δ-agostic methyl complex mer,trans-[RuCl2(PPh3){PPh2CH2C(But)N–NC10H16}]8, in which the methyl group (C10H3) in the 1-position of the fenchone residue interacts with ruthenium (fenchone = 1,3,3-trimethylbicyclo[2.2.1]heptan-2-one). The unsymmetrical camphor azine monophosphine Z,Z-PPh2C10H15N–NC10H169 also gave a similar δ-agostic methyl complex mer,trans-[RuCl2(PPh3){PPh2-C10H15N–NC10H16}]10(camphor = 1,7,7-trimethylbicyclo[2.2.1]heptan-2-one). Treatment of 2 with the azine Z,E-PPh2CH2C(But)N–NCH(C6H4NMe2-4)11a, derived from 4-dimethylaminobenzaldehyde, gave the δ-agostic complex mer,trans-[RuCl2(PPh3){PPh2CH2C(But)N–NCH(C6H4NMe2-4)}]12a, in which the hydrogens in the 2 and 6 positions of the aryl group are agostically interacting with ruthenium. Similarly, the azines 11b and 11c, derived from 4-methoxybenzaldehyde or 4-nitrobenzaldehyde, gave the δ-agostic complexes 12b and 12c, respectively. Treatment of 2 with the azine 13, derived from 1-methylpyrrole-2-carbaldehyde, gave the δ-agostic complex 14, in which the hydrogen in the 3-position of the heterocyclic group is agostically interacting with ruthenium. Treatment of 2 with the azine 15, derived from benzylideneacetone, gave the δ-agostic alkenyl complex 16. Proton, 31P-{1H} and some 13C-{1H} NMR data are given.

Treatment of 0.5 equivalent of [{RhCl(CO)2}2] with the phosphino dimethylhydrazone Z-PPh2CH2C(But)NNMe2(L1) or the phosphino hydrazone Z-PPh2CH2C(But)NNH2(L2) gave the chelate complexes [[graphic omitted]R2}](R = Me 1a or H 1b). Complex 1a reacts with another mole of L1 to give the bis(phosphine)rhodium(I) complex trans-[RhCl(CO)-{PPh2CH2C(But)NNMe2}2]2a. The analogous iridium(I) complex 2b was prepared by treating [IrCl(CO)2(H2NC6H4Me-p)] with 2 mol equivalents of L1. Complex 2a reacts with [PtCl2(cod)](cod = cycloocta-1,5-diene) to give a 1:1 mixture of the chelate 1a and [[graphic omitted]-Me2}]. Treatment of [IrCl(CO)2(H2NC6H4Me-p)] with 2 equivalents of L2 gave the hydridoiridium(III) complex cis-[[graphic omitted]H2}2]Cl 3a. Treatment of [{MCl(cod)}2](M = Rh or Ir) with two equivalents of L1 in methanol in the presence of NH4PF6 gave the cationic complexes [[graphic omitted]Me2}]PF6(M = Rh 4a or Ir 4b) in which L1 is bidentate. When [{MCl(cod)}2] was treated with 2 equivalents of L1 in benzene it yielded the neutral complexes [MCl(cod){PPh2CH2C(But)NNMe2}](M = Rh 5a or Ir 5b) in which L1 is monodentate through phosphorus. Treatment of [{MCl(cod)}2] with 2 equivalents of L2 in CD2Cl2 gave the cationic chelate complexes [[graphic omitted]H2}]Cl (M = Rh 4c or Ir 4d). Treatment of [{RhCl(cod)}2] or [{RhCl(C8H14)2}2](C8H14= cyclooctene) with 2 equivalents of L2 per rhodium atom gave the cationic bis(phosphine)rhodium(I) complex [[graphic omitted]H2}2]Cl 6. Treatment of [RhCl(PPh3)3] with 1 equivalent of L1 in C6D6 gave the Wilkinson-type complex [[graphic omitted]Me2}]7, which readily reacts with dioxygen to give the adduct cis-[[graphic omitted]Me2}]8. The rhodium(III) complex 8 reacts with sulfur dioxide to give the rhodium(III) sulfate cis-[[graphic omitted]Me2}]9. Treatment of [{MCl(C8H14)2}2] with 2 equivalents of L1 per rhodium atom gave the bis(phosphine) complexes cis-[[graphic omitted]Me2}{PPh2CH2C(But)NNMe2}](M = Rh 10a or Ir 10b), containing one chelate and one monodentate phosphine ligand. These complexes reacted rapidly with dioxygen to give corresponding dioxygen adducts cis-[[graphic omitted]Me2}{PPh2CH2C(But)NNMe2}](M = Rh 11a or Ir 11b). Proton, 31P-{1H} and some 13C-{1H} NMR data are given.

The phosphino hydrazone Z-PPh2CH2C(But)NNH21 is shown to be a convenient ‘reagent’ for converting aryl or heterocyclic aldehydes into azines which can then be cycloplatinated readily with C–H, C–I, C–Br, N–H or O–H bond fission. Condensation of 1 with benzaldehyde derivatives (RCHO) gave mixed azines of type Z,E-PPh2CH2C(But)N–NCHR [R = Ph 2a, C6H2(OMe)3-3,4,5 2b, C6H4NO2-4 2c, C6H4I-2 2d, C6H4Br-2 2e, C6H4Cl-2 2f or C6H2(OH-2)(OMe)2-4,6 2g]. The azines 2a–2f reacted with [PtMe2(cod)](cod = cycloocta-1,5-diene) at 20 °C to give dimethylplatinum(II) complexes [[graphic omitted]CHR}]3a–3f respectively, containing six-membered chelate rings. Treatment of 2g with [PtMe2(cod)] effected O–H bond fission to give the O-cyclometallated methylplatinum(II) complex [[graphic omitted](OMe)2-4,6]}]4. When the dimethylplatinum(II) complex 3a was heated in toluene at 100 °C, it underwent C–H bond fission with elimination of CH4 to give the cyclometallated methylplatinum(II) complex [[graphic omitted]C6H4)}]5a. Similarly, 3b and 3c were converted into the corresponding cyclometallated methylplatinum(II) complexes 5b and 5c, respectively. The square-planar dimethylplatinum(II) complex 3d in benzene at 20 °C underwent oxidative addition of the C–I bond to give the cyclometallated iododimethylplatinum(IV) complex mer,cis-[[graphic omitted]H4)}]6a. When the bromo-mixed azine complex 3e was heated in benzene at 75 °C for 16 h the cyclometallated bromodimethylplatinum(IV) complex mer,cis-[[graphic omitted]H4)}]6b formed. In contrast the chloro-mixed azine complex 3f underwent the C–H bond fission and not C–Cl bond fission to give the cyclometallated square-planar methylplatinum(II) complex [[graphic omitted]H3Cl-6)}]5d. The methylplatinum(II) complexes 5a and 5d oxidatively added Mel to give the mer,cis-iododimethylplatinum(IV) complexes 6a and 6c, respectely. Treatment of 1 with 2-carbaldehydes of pyrrole, thiophene or furan gave the corresponding phosphines 7a–7c, which with [PtMe2(cod)] at 20 °C gave the dimethylplatinum(II) complexes 8a–8c, respectively. When 8a, derived from the pyrrole azine phosphine, was heated at 50 °C for 10 min, the N-cyclometallated methylplatinum(II) complex [[graphic omitted])}]9 and methane were formed via a N–H bond fission. When the dimethylplatinum(II) complexes 8b or 8c, derived from the thiophene or furan azine phosphines, were heated at 100 °C in toluene they underwent C–H bond fission to give the cyclometallated methylplatinum(II) complexes [[graphic omitted]H2X)}](X = S 10a or O 10b), which oxidatively added Mel to give the iododimethylplatinum(IV) complexes mer,cis-[[graphic omitted]H2X)}](X = S 11a or O 11b), respectively. Proton, 31P-{1H} and some 13C-{1H} NMR data have been obtained.

Condensation of Z-PPh2CH2C(tBu)NNH2 with 2-halobenzaldehydes gave mixed azines of the type ZE-PPh2CH2C (tBu)NNCH(C6H4X-2) (X = I, 2a; Br, 2b; Cl, 2c; or F, 2e, respectively). 2a, 2b, or 2c reacted with fac-[W(CO)3(NCEt)3] to give tungsten(0) complexes [W(CO)3(NCEt){PPh2CH2C(tBu) NNCH(C6H4X-2)}] (3a–3c), which rapidly underwent oxidative addition to give seven-coordinate tungsten(II) complexes of the type [WX(CO)3{PPh2CH2C(tBu)NNCH(C6H4)}] (4a–4c). The fluoro- mixed azine Ph2PCH2C(tBu)NNCH(C6H4F-2) (2e) with fac-[W(CO)3(NCEt)3] gave [W (CO)3(NCEt){PPh2CH2C(tBu)NNCH(C6H4F-2)}] (3e) which did not undergo CF oxidative addition, but when treated with CO or CNtBu gave tungsten(0) complexes of the type [W(CO)3L{PPh2CH2C(tBu)NCH(C6H4F-2)}] (L = CO, 5a or CNtBu, 5b). The mixed azine from 2-chloro-6-fluorobenzaldehyde and 1 i.e. PPh2CH2C(tBu)NNCH(C6H3Cl-2,-F-6) (2d) with fac-[W(CO)3(NCEt)3] underwent oxidative addition at the CCl bond to give [WCl(CO)3{PPh2CH2C(tBu) NNCH(C6H3F-6)}] (4d) via a tungsten(0) complex 3d. Treatment of the aryl-tungsten(II) complex [WBr(CO)3{PPh2CH2C(tBu)NNCH(C6H4)}] (4b) with NaBH4/CO caused aryltungsten bond fission (reductive elimination) and CN reduction to give the benzylhydrazone-phosphine complex [W(CO)4{PPh2CH2 C(tBu)NNHCH2Ph}] (6) which was also formed by reducing the benzaldehyde mixed azine phosphine tungsten(0) complex [W(CO)4{PPh2CH2C(tBu)NNCHPh}] (8) with NaBH4.

The electrode mechanism of trans-dicarbonyl phosphine complexes of molybdenum(I), trans-[Mo(CO)2(P-P)2]PF6 [where P-P = ph2PCH2CH2Pph2(dppe), or ph2PCH=CHPph2 (dppen)] was investigated by cyclic voltammetry and convolution and deconvolution potential sweep voltammetry in 0.1 mol dm−3 TBAP/CH2Cl2 solution at a platinum electrode. The complexes are both oxidized and reduced in one-electron processes. The oxidation and reduction processes are follows a well-defined ECirrev mechanism. Digital simulation and comparison with the experimental cyclic voltammetric results was used for determination of homogeneous and heterogeneous rate constants values.

Treatment of oxochloro complexes of the type [ReOCl3(L–L)](L–L = diphosphine) with sodium tetrahydroborate gave complexes of the type [ReH7(L–L)]. Treatment of [ReH7(dppen-PP′)]1a[dppen =cis-1,2-bis(diphenylphosphino)ethylene =cis-Ph2PCHCHPPh2] with triphenylphosphine gave a mixture of the pentahydride [ReH5(dppen-PP′)(PPh3)] and the trihydride [ReH3(dppen-PP′)(PPh3)2]. However, treatment of 1a with dppm [bis(diphenylphosphino)methane, Ph2PCH2PPh2] in refluxing toluene, followed by slow crystallisation, gave [ReH5(dppen-PP′)(dppm-P)] which was isolated and characterised by variable-temperature NMR spectroscopy. Prolonged heating of 1a with dppm gave the trihydride [ReH3(dppen-PP′)(dppm-PP′)], the fluxionality of which was studied by NMR spectroscopy between +90 and –70 °C. Protonation of 1a with HBF4·Et2O, at –80 °C, gave a complex formulated as [ReH6(η2-H2)(dppen-PP′)]+ which, on warming to ambient temperature, was cleanly converted to a dirhenium multihydride species tentatively formulated as [(dppen-PP′)H3Re(µ-H)2ReH3(dppen-PP′)] on the basis of IR and NMR evidence.

Treatment of fenchone hydrazone with tert-butyl methyl ketone gave the mixed azine MeC (But)N–NC10H16 which on treatment with LiBun followed by PClPh2 gave the mixed azine monophosphine Z,E-Ph2PCH2C(But)N–NC10H16. This was converted into the corresponding phosphine oxide or phosphine sulfide. The azine monophosphine with [Mo(CO)4(nbd)](nbd = norbornadiene) gave the chelate complex [[graphic omitted]C10H16}] which with L undergoes ring-opening to give [Mo(CO)4L{PPh2CH2C(But)N–NC10H16}](L = CO, CN But or CNMe) with monodentate phosphine. Corresponding tungsten complexes [[graphic omitted]C10H16}] and [W(CO)4L{PPh2CH2C(But)N–NC10H16}](L = CNBut or CNMe) were also prepared. Crystals of Z,E-Ph2PCH2C(But)N–NC10H16 are monoclinic, space group P21 with a= 11.0737(8), b= 11.0377(9), c= 11.1072(7)A, β= 110.60(5)° and Z= 2 for 3492 observed reflections. Proton, 31P-{1H}, 13C-{1H} NMR, IR and mass spectral data are given.

Treatment of the azine diphosphine Z,Z-PPh2CH2CButN–NCButCH2PPh2I with [PtCl2(cod)](cod = cycloocta-1,5-diene) in CHCl3 in the presence of NEt3 gave the neutral deprotonated chloroplatinum(II) complex [[graphic omitted]Ph2)], containing an ene–hydrazone backbone. The corresponding bromo- and iodo-analogues were prepared from it by metathesis. The analogous chloropalladium(II) complex was prepared by treating I with [PdCl2(NCPh)2] in the presence of NEt3. Treatment of it with LiBr or MgMel gave the corresponding bromo- and methyl-palladium(II) complexes, respectively. Treatment of the neutral complexes [[graphic omitted]Ph2)](M = Pt or Pd) with acids (HX) reprotonated the ene–hydrazone backbone to give the salts [[graphic omitted]Ph2)]X 4[X = picrate, formate or (1S)-7,7-dimethyl-2-oxobicyclo[2.2.1]heptane-1-methanesulfonate, M = Pt or Pd]. Treatment of [[graphic omitted]Ph2)] with 0.5 equivalent of NH2NH2·2HCl gave a mixture of the nine-membered ring complex [[graphic omitted]Ph2)] and its isomerie chloride salt [[graphic omitted]Ph2)]Cl. When [[graphic omitted]Ph2)], containing a nine-membered chelate ring, was heated to 75 °C in C6H6 the methylplatnum(II) complex, [[graphic omitted]Ph2)], containing the terdentate dehydroazine ligand, was formed by oxidative addition of NH followed by reductive elimination of CH4. Treatment of the same PtMe2 complex with 1 equivalent of picric acid gave the picrate salt [[graphic omitted]Ph2)][OC6H2(NO2)3], which with 1,8-diazabicyclo[5.4.0]undec-7-ene (dbu) gave [[graphic omitted]Ph2)], and with Mel followed by NH4PF6 gave fec-[[graphic omitted]Ph2)]PF6 which with dbu gave fac-[[graphic omitted]Ph2)]. Treatment of [[graphic omitted]Ph2)] with 1 equivalent of picric acid gave [[graphic omitted]Ph2)][OC6H2(NO2)3] which with dbu gave [[graphic omitted]Ph2)]. Treatment of I with [Pt(nb)3](nb = norbornene) gave the bridged binuclear platinum(0) complex [Pt2(nb)2(µ-PPh2CH2CButN–NCButCH2PPh2)2], containing an 18-atom ring. Treatment of this with MeO2CCCCO2Me displaced the norbornene to form the corresponding bis(dimethyl acetylenedicarboxylate) complex. When the former was heated to 75 °C in benzene [[graphic omitted]Ph2)] was formed. The bis(norbornene)platinum(0) complex also underwent oxidative addition with Mel to give [[graphic omitted]Ph2)]I, which with dbu gave [[graphic omitted]Ph2)]. Methods of forming the di- and tetra-deuteriated complexes containing the azine backbone, and also mono- and tri-deuteriated complexes containing the dehydroazine backbone are discussed (M = Pt or Pd). A novel method of functionalising (e.g. alkylation and halogenation) the ligand backbone by electrophilic attack on the enamine carbon in complexes of type 4 is described. The crystal structures of [[graphic omitted]Ph2)] and [[graphic omitted]Ph2)][OC6H2(NO2)3] were determined. Proton. 31P and some 13C NMR data are given.

New 2,3,6,7-tetraaza-1,3,5,7-octatetraene (α-diazine) derivatives camphN–NCH–CHN–Ncamph I, where camph is a (1R)-(+)-camphor residue, C10H16, and fenchN–NCH–CHN–Nfench II, where fench is a 1R-(–)-fenchone residue, C10H16, have been obtained together with the 2′-pyridyl derivatives CamphN–NCHC5H4N III and fenchN–NCHC5H4N IV. The configurations around the four CN bonds of I or II are E,E,E,E whilst those around the two azine CN bonds in III and IV are E,E. Complexes of the types [M(CO)4L](M = Cr, Mo or W; L =I–IV), [Mo(CO)3LL′](L =I, L′= NCMe, PPh3 or AsPh3; L =II–IV, L′= PPh3), [Mo(CO)2L(PPh3)2](L =III or IV) and [Mo(CO)2Br(η3–CH2CHCH2)L](L =I, III or IV) containing these azines as ligands have also been obtained. Complexes of II are the most unstable and these together with tetracarbonyl complexes of IV appear to show restricted rotation around the N–N bond(s) caused by the steric requirements of the methyl groups on the fenchone residue(s). All the complexes have been characterised by multinuclear NMR (1H, 13C and 31P), IR and UV/VIS spectroscopies and mass spectrometry. The crystal structures of camphN–NCH–CHN–Ncamph I and fenchN–NCHC5H4N IV have been determined.

tert-Butyl diphenylphosphinomethyl ketone dimethylhydrazone L1 reacts with [PtCl2(cod)](cod = cycloocta-1,5-diene) to give the chelate [[graphic omitted]Me2}] with a six-membered chelate ring; the corresponding palladium complex was also prepared. The phosphino dimethylhydrazone L1 or the phosphino hydrazone L2 also react with [PtMe2(cod)] to give [[graphic omitted]R2}], (R = Me or H); these platinum(II) complexes react with methyl iodide to give the corresponding trimethylplatinum(IV) complexes [[graphic omitted]R2}]. Treatment of [PtCl2(cod)] with 2 equivalents of L2 gave the dication cis-[[graphic omitted]H2}2]2+ isolated as the chloride or chloride hexafluorophosphate salts. The dicationic dichloride reacted with 2 moles of sodium ethoxide to give the neutral cis-[[graphic omitted]H}2]. Treatment of [PdCl2(NCPh)2] with L2 gave [[graphic omitted]H2}2]Cl2, which with sodium ethoxide gave the neutral trans-[[graphic omitted]H}2]. The mixed azine monophosphine PPh2CH2C(But)N–NCHPh L3 with [PdCl2(NCPh)2] gave the chelate complex [[graphic omitted]CHPh}] and with [PtMe2(cod)]it gave [[graphic omitted]CHPh}]. Treatment of [PtCl2(NCMe)2] with 2 equivalents of L3 gave trans-[PtCl2{PPh2CH2C(But)N–NCHPh}2] which on heating gave the dicationic dichloride salt cis-[[graphic omitted]–NCHPh}2]Cl2. Successive treatments of this salt with 1 mole of sodium methoxide gave cis-[{[graphic omitted]–NCHPh}]+ and cis-[{[graphic omitted]–NCHPh}2]. Proton, 13C –{1H}, 31P –{1H} NMR and infrared data have been obtained. Crystals of cis-[[graphic omitted]H2}2] are monoclinic, space group P21/c, with a= 1261.5(2), b= 1794.6(3), c= 1792.0(4) pm and Z= 4; final R= 0.0451 for 4088 observed reflections.

Condensation of Z-PPh2CH2C(But)NNH2 with salicylaldehyde or 4,6-dimethoxysalicylaldehyde gave the azine phosphines Z,E-PPh2CH2C(But)N–NCH(C6H4OH-2)1a or Z,E-PPh2CH2C(But)N–NCH[C6H2(OH-2)(OMe)2-4,6]1b, respectively. Treatment of 1a with [PdCl2(cod)](cod = cyclo- octa-1,5-diene) gave the bidentate chelate complex [[graphic omitted]CH(C6H4OH-2)}]3. The phosphine 1a reacts with Na2PdCl4 in the presence of NaO2CMe to give the terdentate chelate complex [[graphic omitted])}]4a Treatment of the latter with Nal or MgMel gave the corresponding iodopalladium(II) complex 4b or the methylpalladium(II) complex 4c, respectively. The analogous methylplatinum(II) complex [[graphic omitted])}]4d was prepared by treating [PtMe2(cod)] with 1a. Fluxional nickel(II) complexes of type [[graphic omitted])}](X = Cl 4e or Br 4f) were also prepared from NiX2·nH2O. When Ni(O2CMe)2·4H2O was treated with two mol equivalents of 1a a paramagnetic octahedral nickel(II) complex [[graphic omitted])}2]5 was formed. Treatment of [PtCl2(cod)] with two mol equivalents of 1a in the presence of NaO2CMe gave a monocationic platinum(II) chloride salt, which with NH4PF6 gave the PF6 salt. Treatment of 1b with [IrCl(CO)2(MeC6H4NH2-p)] or 0.5 equivalents of [Rh2Cl2(CO)4] in the presence of NEt3 gave the square-planar complexes [[graphic omitted](OMe)2-4,6]}](M = Ir 7a or Rh 7b). The carbonyliridium(I) complex 7a underwent oxidative-addition reactions with Mel, allyl chloride, acetyl chloride or propargyl chloride to give the halogenocarbonyliridium(III) complexes [[graphic omitted](OMe)2-4,6]}]8a–8d respectively. In contrast, the reaction of the carbonylrhodium(I) complex 7b with allyl chloride gave the π-allylrhodium(III) complex [[graphic omitted](OMe)2-4,6]}]9. Proton, 31P-{1H} and some 13C-{1H} NMR data have been attained.

Treatment of [Cr(CO) 4 (nbd)] (nbd  norbornadiene) with Z , Z -PPh 2 CH 2 C( t Bu)NNC( t Bu)CH 2 PPh 2 gave the title compound 2b , the structure of which was determined by a single crystal X-ray diffraction study. The proton NMR spectrum of 2b at 308 K and 400 MHz showed that for each of the methylene groups the protons are equivalent, but the spectrum is temperature dependent and at 188 K the slow exchange limiting spectrum is obtained, with all methylene hydrogens chemically non-equivalent; corresponding changes were observed in the 13 C-{ 1 H} NMR spectrum. The behaviour is due to the fluxionality of the 9-membered ring.

Analysis of the 13 C{ 1 H} NMR spectrum of Z,Z -PPh 2 CH 2 C(Bu t )NNC(Bu t )CH 2 PPh 2 ( 1 ) gives second order patterns for the C ipso , C ortho , C meta , P C H 2 and CN carbons caused by a non-zero seven-bond coupling, 7 J (PP). Simulation of the spectra gives 7 J (PP)=4.8 Hz. The corresponding diphosphine dioxide 2 gives first order 13 C{ 1 H} spectra, i.e. 7 J (PP) ∼ 0 Hz. Possible explanations for this unusually large value of 7 J (PP) are discussed. Crystals of 2 are orthorhombic, space group Pbca , with a =1592.2(3), b =1196.1(2), c =1663.0(3) pm and Z =4; final R factor 0.0381 for 1780 observed reflections.

The azine diphosphine Z,ZPPh2CH2C(But)N–NC(But)CH2PPh2I was treated with [Pt-Me2(cod)](cod = cycloocta-1,5-diene) to give the dimethylplatinum(II) complex [[graphic omitted]Ph2}]1a containing a nine-membered chelate ring with an E,Z configuration for the bidentate azine diphosphine ligand. This complex undergoes oxidative addition with Mel to give the fac-trimethylplatinum(IV) complex [[graphic omitted]PPh2}]2. The corresponding platinum(II) complexes [[graphic omitted]PPh2}](X CCC6H4Me-p1b or Cl 1c) were also prepared. Treatment of trans-[PtCl2(NCR)2](R = Me or Ph) with I gave a hexanuclear species trans-[{PtCl2[PPh2CH2C(But)N–NC(But)CH2PPh2]}6]3a in which the azine diphosphine is acting as a bridging group and is still symmetrical, i.e. the configuration is still Z,Z. The palladium analogue 3b was made by treating [PdCl2(NCPh)2] or Na2[PdCl4] with 1 but might only be binuclear. This complex was unstable in hot chloroform and at 60 °C (30 min) was completely converted into the salt [[graphic omitted]PPh2}]Cl 4a in which the azine diphosphine is tridentate with E,Z configuration and mutually trans-co-ordinated phosphorus donors and one of the azine nitrogens is co-ordinated. Treatment of [PtCl2(cod)] with I and addition of NH4PF6 gave the platinum salt [[graphic omitted]PPh2}]PF64c; [[graphic omitted]PPh2}]I 4d was also prepared. On prolonged (8 d) heating in chloroform solution the bridged complex 3b was quantitatively converted into the novel and very stable heterocyclic complex [[graphic omitted]PPh}]5a with loss of a molecule of benzene. Treatment of 5a with LiBr or Nal gave the corresponding dibromide 5b or diiodide 5c complexes. The crystal structure of 5c has been determined. The corresponding platinum complexes [[graphic omitted]PPh}]5d-5f(X = Cl, Br or I) were also prepared and treatment of the dichloro complex with MgMel gave the dimethyl complex 5g. Treatment of this dimethyl complex with an excess of Mel gave [[graphic omitted]PPh}]6. Proton, 13C-{1H} and 31P-{1H} NMR and infrared data are given.

Treatment of lithiated d-camphor with a half molar equivalent of PPh2Cl gives the 3-diphenylphosphino enolate anion [PPh2(C10H14O)]− as the only phosphorus-containing species. Treatment of lithiated d-camphor with one equivalent of PPh2Cl gives some of the enolate anion but the main product is the 3-exo substituted camphor derivative 3-exo-PPh2(C10H15O) together with some of the 3-endo-substituted derivative. On storage of the solution, the 3-endo substituted derivative becomes the main product with some of the 3-exo-substituted derivative still present. Treatment of a solution of the enolate ion with Na2PdCl4 · 4H2O gives or with PtCl2(cyclo-octa-1,5-diene), cis- is formed. Treatment of these bis-chelate complexes with hydrogen chloride opens up the chelate rings reversibly, giving dichloro-complexes of type [MCl2{(PPh2)C10H15O}2] {M = Pd (trans-isomer) M = Pt (cis-isomer)}. Treatment of ethanol or methanol solution of these bischelate complexes with acetylenes, especially in the presence of traces of acetic acid also opens up the chelate rings to give di-acetylides of type [M(CCR)2{(PPh2)C10H15O}2] {M = Pd or Pt; R = Ph or C(Me) = CH2}. When treated with HCCH or EtCCH the bis-chelate gives the corresponding acetylides but these could not be isolated and reverted to the starting bis-chelate complex, i.e. acetylide formation is reversible.

Treatment of (1R)-(+)-camphor with LiBun, followed by Ph2PCl gives, as the main product, exo-3-diphenylphosphino- (1R)-(+)-camphor (3a) together with some of the corresponding enolate anion 1. However, on storage the exo- phosphine 3a isomerises to the corresponding endo-phosphine 3b which becomes the main product and was isolated in 70% yield. The crystal structure of 3b was determined and detailed 13C and proton NMR data are given. In chloroform solution, in the presence of acetic acid as catalyst, the endo-phosphine 3b is partially converted back into the exo-isomer 3a over 2 days. The endo-phosphine 3b (L) with H2O2 gives the corresponding phosphine oxide 3c and with monoclinic sulfur the corresponding phosphine sulfide 3d. With [PdCl2(NCPh)2] the endo-phosphine 3b gives [PdCl2L2] which exists as a cis-trans mixture 4a and 4b in solution. We have determined the X-ray crystal structure of the cis-form 4b. Treatment of [PtCl2(COD)] with L, gives cis-[PtCl2L2] (4c) but with [PtCl2(NCMe)2] the corresponding trans complex trans-[PtCl2L2] (4d) is formed. In compounds 4a-4d the PPh2 groups are endo. The complexes of type [MCl2L2] (MPd or Pt) are also formed by treating the bis-camphorphosphine enolates [M(PPh2C10H14O)2] with HCl. The complexes of type cis-[Pt(CCR)2(PPh2C10H15O)2] (RPh or C(Me)CH2) with HCl give exclusively cis-[PtCl2L2]. Treatment of [Rh2Cl2(CO)4] with the endo-phosphine 3b (L) gives trans-[RhCl(CO)L2]. 1H, 31P and some 13C data are given. Crystals of endo-3-diphenylphosphino-(1R)-(+)-camphor (3b) are orthorhombic, space group P212121 with a=778.6(1), b=1138.8(1), c=2128.9(3) pm and Z=4, R=0.0329 for 1674 observed reflections. The structure shows that the PPh2 is endo. Crystals of 4b are orthorhombic, space group P212121, with a=1380.3(2), b=1785.1(3), c=1922.8(4) pm and Z=4, R=0.0425 for 4438 observed reflections. The structure shows that the PPh2 groups are endo and that the phosphines are cis.

Treatment of the molybdenum tetracarbonyl complex of 3-diphenylphosphino-(1R)-(+)-camphor dimethylhydrazone [Mo(CO)4(PPh2C10H15NNMe2] (1a) with hydrogen chloride effects a rapid Redox/Fission reaction to give the molybdenum(II) imine complex [Mo(CO)3Cl2(PPh2C10H15NH)] (2a). Other strong acids HX reacted similarly to give analogous complexes [Mo(CO)3X2(PPh2C10H15NH)] (X = Br, I or OOCCF3). Reduction of 2a with sodium borohydride in the presence of carbon monoxide gave [Mo(CO)4(PPh2C10H15NH)] (1b), the crystal structure of which was determined. Treatment of 1b with LiN(SiMe3)2, followed by MeI gave [Mo(CO)4(PPh2C10H15NMe)] (1c). Treatment of 1a with bromine gave the tricarbonylmolybdenum(II) complex [Mo(CO)3Br2(PPh2C10H15NNMe2)] (2e). NMR and IR data, and bond length/bond angle data for 1b, are given.

Treatment of tert-butylmethyl ketone dimethylhydrazone with LiBu, followed by PPh2Cl, gave the crystalline phosphino dimethylhydrazone PPh2CH2C(But)NNMe22a having the CNNMe2 group in the Z configuration. This phosphine with [Mo(CO)4(nbd)](nbd = norbornadiene) gave [[graphic omitted]Me2}]3a, with a six-membered chelate ring; the corresponding tungsten 3b and chromium 3c complexes were made similarly. When phosphine 2a was heated with [Mo(CO)6] some 3a was formed together with the isomeric complex [[graphic omitted]NMe2}]4, with a five-membered chelate ring and an E arrangement around CNNMe2. When 3a was heated in diglyme [MeO(CH2)2O(CH2)2OMe] to ca. 150 °C the phosphino imine complex [[graphic omitted]H}]5 was formed. Compound 2a with hydrazine gave the corresponding phosphino hydrazone 2c, containing a CNNH2 moiety, in over 90% yield. The phosphines 2a or 2c, with sulfur, gave the corresponding phosphine sulfides. The phosphine 2c with [M(CO)4(nbd)] gave [[graphic omitted]H2}](M = Mo 3d, W 3e or Cr 3f). When 3d was heated in diglyme to ca. 150 °C it also gave complex 5. The oxidation of molybdenum(0) complex 3d with bromine gave the seven-co-ordinate molybdenum(II) complex [[graphic omitted]H2}]6. Compound 2c was condensed with benzaldehyde to give the phosphino mixed-azine PPh2CH2C(But)NNCHPh 7a, which with H2O2 formed the phosphine oxide 7b. The phosphine 7a reacted with [M(CO)4(nbd)] to give [[graphic omitted]CHPh}](M = Mo 8a, W 8b or Cr 8c). Complex 8a with bromine gave the seven-co-ordinate molybdenum(II) complex [[graphic omitted]CHPh}]9. Crystals of complex 3a are monoclinic, space group P21/n with a= 892.3(1), b= 1920.1(3), c= 1493.6(3) pm, β= 105.67(1)° and Z= 4, R= 0.0250 for 3530 observed reflections. The structure shows that the CNNMe2 group has the Z configuration and that the NMe2 group is co-ordinated to molybdenum, giving a six-membered ring.

Treatment of [PtX2(cod)](cod = cycloocta-1,5-diene) with the diphosphine (Ph2PCH2)2CCH2 gives the complexes [PtX2{(Ph2PCH2)2CCH2}](X = Cl 1a or Me 1c). The dichloro complex can be converted to give the corresponding diiodo complex by metathesis and isomerised by base (NaOH–EtOH) to give [PtCl2(Ph2PCH2CMeCHPPh2)]2a. Treatment of complexes 1a, 1c or 2a with LiMe gives [PtMe2{(Ph2PCH)2CMe}]–3, containing a symmetrical anionic diphosphine, which reacts with MeOH to give [PtMe2(Ph2PCH2CMeCHPPh2)]2b. Treatment of 1a or 2a with equimolar amounts of Cl2 produces the corresponding tetrachloroplatinum(IV) complexes 4 and 5, whilst treatment of 1c with MeI gives [PtMe3I{(Ph2PCH2)2CCH2}]6; 4–6 are all unstable in solution with respect to reductive elimination reactions, 4 and 5 giving 1a and 2a respectively whilst 6 gives [PtMeI{Ph2PCH2)2CCH2}]. Treatment of 3 with electrophilic reagents such as MeI, PhCH2Br, SiMe3Cl or PPh2Cl gives complexes [PtMe2(Ph2PCHRCMeCHPPh2)](R = Me 7a, PhCH27b, SiMe37c or PPh27d). Treatment of the salt [Pt{(Ph2PCH2)2CCH2}2]Cl29 with NaBH4 gives the platinum(0) compound [Pt{(Ph2PCH2)2CCH2}2]9, whilst with LiBu–Me2NCH2CH2NMe2 it gives the unusual platinum(II) complex [[graphic omitted]HPPh2}2]10, in which the Pt is bonded to two P and two C atoms and two of the phosphorus atoms are uncomplexed.

Treatment of the azine MeC(But)NNC(But)Me with 2 equivalents of LiBun, followed by 2 equivalents of PPh2Cl, gives the azine diphosphine Z,Z-PPh2CH2C(But)N–N(But)CCH2PPh21. This new diphosphine was treated with H2O2 to give the corresponding diphosphine dioxide 2a and with monoclinic sulfur to give the diphosphine disulfide 2b. Treatment of [M(CO)3(η6-cht)](cht = cyclohepta-2,4,6-triene) with 1 gave the metal tricarbonyl fac-[[graphic omitted]Ph2}](M = Mo, 3a; W, 3b; or Cr, 3c) in which the azine diphosphine is bonded in the E,Z configuration. Complexes 3a and 3b were also made by treating the corresponding metal hexacarbonyls with the azine diphosphine 1. Treatment of [M(CO)4(nbd)](M = Mo, W, or Cr; nbd = norbornadiene) with 1 gave the tetracarbonyl complexes [[graphic omitted]Ph2}]4 with the E,Z-azine diphosphine acting as a bidentate ligand. On heating, these tetracarbonyl complexes 4 were converted into the tricarbonyl complexes 3. Treatment of either 3a or 4a with 1 mol equivalent of bromine gave the neutral molybdenum(II) complex [[graphic omitted]Ph2}]5, whereas the tungsten complexes 3b and 4b with bromine gave the cation [[graphic omitted]Ph2}]+ isolated as its BPh4– salt 6. Proton, 13C-{1H} and 31P-{1H} NMR and infrared data are given. Crystals of 1 are monoclinic, space group P21/n, with a= 1667.2(2), b= 572.85(6), c= 1811.0(2) pm, β= 111.595(8)° and Z= 2; final R factor 0.0519 for 2049 observed reflections. Crystals of 3a are monoclinic, space group P21/n, with a= 985.7(1), b= 1870.2(2), c= 2220.8(2) pm, β= 93.71(1)° and Z= 4, final R factor 0.0354 for 5219 observed reflections.