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N,N′-Diphenylamidines, PhNC(R)NHPh (R=H, Me, Et, Ph), and 1,3-diaryltriazenes, ArNNNHAr (Ar=p-C6H4X, X=H, Cl, Me, OMe) react with ruthenium(II) complexes, [RuCl2(C7H8)]n, [RuCl2(CO)2]n and [RuCl2(Me2SO)4] in the presence of a base (NEt3 or Na2CO3) to afford a selection of bis(chelate) products [Ru{PhNC(R)NPh}2L2] and [Ru(ArNNNAr)2L2] (L=CO, Me2SO; L2=C7H8). In contrast one particular combination — [RuCl2(Me2SO)4]/PhNC(H)NHPh/NEt3 — in refluxing dimethylformamide yields a novel amidine fragmentation product [RuCl(NH2Ph){PhNC(H)NPh}(Me2SO)2] which has been characterised by X-ray diffraction methods.

N,N′-Diphenylthiourea reacts with [RuHCl(CO)(PPh3)3] and [Ru(H)2(CO)(PPh3)3] in refluxing benzene to afford the N,N′-diphenylthioureido complexes [RuCl{PhNC(NHPh)S}(CO)(PPh3)2] and [RuH{PhNC(NHPh)S}(CO)(PPh3)2], respectively. Under more forcing conditions in refluxing toluene the precursors [MHCl(CO)(PPh3)3] (M=Ru or Os) and [Os(H)2(CO)(PPh3)3] afford the thioureido complexes [M{PhNC(NHPh)S}2(CO)(PPh3)] and the known N-phenylthioformamidato complex [OsH{PhNC(H)S}(CO)(PPh3)2], respectively. The reaction of [RuCl2(PPh3)3] with N,N′-diphenylthiourea and triethylamine in boiling toluene yields [Ru{PhNC(NHPh)S}2(PPh3)2]. Finally the reaction of mer-[Ir(H)3(PPh3)3] with N,N′-diphenylthiourea in boiling toluene affords [Ir(H)2{PhNC(NHPh)S}(PPh3)2]. Spectroscopic evidence indicates that the N,N′-diphenylthioureido anions are bound as N,S chelates, and this coordination mode has been confirmed for [Ru{PhNC(NHPh)S}2(CO)(PPh3)] by an X-ray crystal structure determination. Trends in exocyclic CNR2 bond lengths for related guanidinato, thioureido and dithiocarbamato complexes are reported.

Reactions of [RuCl 2 (Me 2 SO) 4 ] with silver carboxylates, [Ag(O 2 CR)] (R=Me, CF 3 ) in cold dichloromethane afford the title compounds, [Ru(O 2 CR) 2 (H 2 O)(Me 2 SO) 3 ] in good yield as pale cream crystals. X-ray crystal structure determinations have been performed on both complexes. In each case the geometry about the ruthenium centre is essentially octahedral with three S-bonded Me 2 SO ligands arranged in a fac configuration, two monodentate carboxylate anions and a coordinated H 2 O molecule. The carboxylate ligands are H-bonded to the H 2 O ligand via their non-coordinated oxygen atoms. The structures are compared with those previously reported for the alcohol dehydrogenation catalyst [Ru(O 2 CCF 3 ) 2 (MeOH)(CO)(PPh 3 ) 2 ] and a closely related ruthenium carboxylate complex [Ru(O 2 CCF 3 ) 2 (H 2 O)(PMe 3 ) 3 ].

N,N′,N″-Triphenylguanidine (TpgH) reacts with [Ru(H)2(CO)(PPh3)3] in refluxing toluene and with [Os(H)2(CO)(PPh3)3] in refluxing o-xylene to yield the guanidinate(−1) complexes [RuH(Tpg)(CO)(PPh3)2] (1) and [Os(Tpg)2(CO)(PPh3)] (2), respectively. The reaction of TpgH with [RuCl2(PPh3)3] in refluxing toluene affords a new route to the known complex [Ru(Tpg)2(CO)(PPh3)] (3). Finally the reaction of mer-[Ir(H)3(PPh3)3] with TpgH in refluxing toluene yields the iridium(III) dihydride complex [Ir(H)2(Tpg)(PPh3)2] (4). X-ray crystal structure determinations are reported for (1) and (4).

N,N′,N″ -Triphenylguanidine (HTpg) reacted with [Ru(O2CCF3)2(CO)(PPh3)2] in boiling toluene to yield [Ru(Tpg)2(CO)(PPh3)], the first example of a mononuclear complex containing two chelate guanidinate(1–) ligands. Palladium(II) acetate reacted with HTpg in warm benzene to form an adduct [Pd(O2CMe)2(HTpg)2] which, under more forcing conditions, converts into the novel binuclear guanidinate(1–) bridged complex [{Pd(µ-Tpg)(Tpg)}2]. Crystal structures have been determined for both guanidinate(1–) complexes.

Thiobenzamide reacted with the complexes [MCl 2 (PPh 3 ) 3 ], [MH(X)(CO)(PPh 3 ) 3 ] (M = Ru or Os, X = H or Cl) and mer-[IrH 3 (PPh 3 ) 3 ] in boiling toluene to afford the products [M{S(NH)CPh} 2 (PPh 3 ) 2 ], [MX{S(NH)CPh}(CO)(PPh 3 ) 2 ] and [IrH 2 {S(NH)CPh}(PPh 3 ) 2 ] respectively. The crystal structure of [Os{S(NH)CPh} 2 (PPh 3 ) 2 ] confirms the expected bis(N,S-chelate) formulation and has established the presence of cis-phosphorus, cis-nitrogen and trans-sulfur donor atom pairs within a highly distorted octahedral co-ordination sphere. Thiobenzoic acid reacted with [MCl 2 (PPh 3 ) 3 ] and [MH(X)(CO)(PPh 3 ) 3 ] under similar conditions to yield [M{S(O)CPh} 2 (PPh 3 ) 2 ] and [M{S(O)CPh} 2 (CO)(PPh 3 ) 2 ] respectively. The reactions of thiobenzoic acid with mer-[IrH 3 (PPh 3 ) 3 ] under conditions of increasing severity give [IrH 2 {S(O)CPh}(PPh 3 ) 3 ], [IrH{S(O)CPh} 2 (PPh 3 ) 2 ] and [Ir{S(O)CPh} 3 (PPh 3 ) 2 ] the last two of which on carbonylation afford [IrH{S(O)CPh} 2 (CO)(PPh 3 ) 2 ] and [Ir{S(O)CPh} 3 (CO)(PPh 3 ) 2 ] respectively. The crystal structure of [IrH{S(O)CPh} 2 (PPh 3 ) 2 ] has established the presence of trans phosphorus and trans sulfur donor atom pairs, with the η 1 - and η 2 -thiobenzoate ligands sharing a meridional set of three co-ordination sites. However, the NMR spectra of this complex show two high-field 1 H triplets and two 31 P-{ 1 H} singlets. Possible explanations for this anomalous NMR behaviour, which is also found for the corresponding thioacetate, are advanced.

N,N′-Diphenylguanidine reacted with the hydrido complexes [MH 2 (CO)(PPh 3 ) 3 ] (M = Ru or Os) and mer-[IrH 3 (PPh 3 ) 3 ] in boiling toluene to afford the complexes [MH{PhNC(NH 2 )NPh}(CO)(PPh 3 ) 2 ] and [IrH 2 {PhNC(NH 2 )NPh}(PPh 3 ) 2 ] in which the N,N′-diphenylguanidinate anions adopt a symmetrical chelate co-ordination mode. Under similar conditions the trifluoroacetato complexes [M(O 2 CCF 3 ) 2 (CO)(PPh 3 ) 2 ] afforded salts [M{PhNC(NH 2 )NPh}{PhNC(NH 2 )NPh ·H}(CO)(PPh 3 ) 2 ][O 2 CCF 3 ] containing one chelate N,N′-diphenylguanidinate anion and one monodentate N,N′-diphenylguanidine ligand. Spectroscopic evidence indicates that the trifluoroacetate anions are hydrogen bonded to one or more of the N-bound hydrogens.

The ruthenium(I) amidinato complex [Ru{PhNC(Me)NPh}(CO)3]2 has been prepared by heating [Ru3(CO)12] with the free amidine, PhNC(Me)NHPh, in boiling benzene under a carbon monoxide atmosphere, and by heating [{Ru(O2CMe)(CO)2}2]n with free amidine and triethylamine in acetonitrile under carbon monoxide. The structure of [Ru{PhNC(Me)NPh}(CO)3]2 has been determined by X-ray diffraction methods. The binuclear complex has two Ru(CO)3 units linked by an RuRu bond [2.714(1) A] and a cis pair of bridging amidinato ligands. Variable temperature 1H and 13C {1H} NMR spectra show evidence of hindered rotation about the Nphenyl bonds of the amidinate ligands. An attempt to prepare the corresponding propionamidinate derivative gave a product which is tentatively formulated as [Ru{PhNC(Et)NPh}(CO)2(HO2CMe)]2 on the basis of analytical and spectroscopic evidence.

N,N′-Diphenylamidines PhNC(R)–NHPh (R = H, Me, Et or Ph) reacted with the precursors [MH2(CO)(PPh3)3], [MH(Cl)(CO)(PPh3)3] and [M(O2CCF3)2(CO)(PPh3)2]·nMeOH (M = Ru, n= 0.75; or Os n= 0.33) in boiling benzene to afford the amidinato complexes [MH{PhNC(R)NPh}(CO)(PPh3)2], [MCl{PhNC(R)NPh}(CO)(PPh3)2] and [M(O2CCF3){PhNC(R)NPh}(CO)(PPh3)2] respectively. The hydrides [MH{PhNC(R)NPh}(CO)(PPh3)2] have also been obtained by oxidative addition of amidines to [Ru(CO)3(PPh3)2] and by treatment of the precursors [MH(Cl)(CO)(PPh3)3] with amidines in the presence of an excess of base (NEt3). The trifluoroacetates [M(O2CCF3)2(CO)(PPh3)2]·nMeOH reacted with amidines in the presence of NEt3 to afford the hydrides [MH{PhNC(R)NPh}(CO)(PPh3)2](M = Ru, R = H; M = Os, R = H, Me, Et or Ph) or the bis(amidinato) complexes [M{PhNC(R)NPh}2(CO)(PPh3)](M = Ru; R = Me, Et or Ph). Reactions of the dichlorides [MCl2(PPh3)3] with amidines and base (NEt3) in boiling toluene containing traces of alcohol were accompanied by a carbonyl-abstraction reaction leading to formation of [MH{PhNC(R)NPh}(CO)(PPh3)2] and/or [MCl{PhNC(R)NPh}(CO)(PPh3)2]. The hydrides [MH{PhNC(R)NPh}(CO)(PPh3)2] are also obtained when [RuH2(PPh3)4] or [OsH4(PPh3)3] reacts with amidines in boiling toluene (containing a trace of alcohol) or in 2-methoxyethanol. The carbonyl abstractions are remarkable in that they have no parallel in the corresponding reactions involving the related triazenide (PhNNNPh–) and carboxylate (RCO2–) ligands even when neat alcohols are used as solvents. Reactions of mer-[IrH3(PPh3)3], [IrHCl2(PPh3)3]–NEt3 and [IrHCl2(PPh3)3] with amidines in boiling benzene or toluene afforded [IrH2{PhNC(R)NPh}(PPh3)2], [IrH(Cl){PhNC(R)NPh}(PPh3)2] and [IrCl2{PhNC(Ph)NPh}(PPh3)2] respectively.

Succinimide reacts with [RuHCl(PPh3)3] in refluxing toluene to afford a maroon air-stable complex 1. A crystal of 1 obatained from CH2Cl2–MeOH solution has been shown by X-ray diffraction methods to possess the succinimido-bridged structure [Ru2(µ-Cl)(µ-H)(µ-C4H4NO2)2(PPh3)4]·2CH2Cl2·0.5H2O. Succinimide also reacts with [RuCl2(PPh3)3] in refluxing toluene in the presence of an excess of NEt3 to form a closely related monocarbonyl derivative [Ru2(µ-Cl)(µ-H)(µ-C4H4NO2)2(CO)(PPh3)3]2 as orange needles. Carbonylation of 2 in refluxing toluene affords the dicarbonyl [Ru2(µ-Cl)(µ-H)(µ-C4H4NO2)2(CO)2(PPh3)2]3 as pale yellow crystals. The products 1–3 have been characterised by infrared and 1H and 31P-{1H} NMR spectroscopies.

Ruthenium(II) and osmium(II) complexes [MCl2(PPh3)3] undergo oxidative-substitution reactions with N,N′-diphenylamidines PhNC(R)–NHPh (R = H, Me, Et or Ph) under mild conditions to form the ruthenium(III) and osmium(III) products [MCl2{PhNC(R)NPh}(PPh3)2](M = Ru; R = H or Ph; M = Os, R = H, Me or Ph). However, in contrast to other systems of this type, more prolonged reaction times lead to further substitution and/or oxidation steps which afford the ruthenium(III) complexes [RuCl{PhNC(R)NPh}2(PPh3)] and the osmium(IV) species [OsCl2{PhNC(R)NPh}2](R = Me, Et or Ph). The crystal structure of trans-[OsCl2{PhNC(Et)NPh}2] has been determined.

Homoleptic tris(triazenido) derivatives of ruthenium, osmium, rhodium and iridium, M(ArNNNAr) 3 (Ar = p -C 6 H 4 X; X = H, Me or Cl), have been prepared by treatment of the chlorides or chloro complexes—RuCl 3 (aq.), (NH 4 ) 2 OsCl 6 (aq.), RhCl 3 (aq.) and (NH 4 ) 2 IrCl 6 (aq.), respectively—with excess 1,3-diaryltriazene and triethylamine in boiling ethanol (M = Ru, Rh) or aqueous ethanol (M = Os, Ir). The sparingly soluble, air-stable, deep green (M = Ru, Os) or red-orange (M = Rh, Ir) complexes have been characterized by vibrational and NMR spectroscopy, and by magnetic measurements.

The binuclear ruthenium(I, I) triazenido complex [Ru2(RNNNR)2(CO)6](R =p-tolyl) reacts with excess of 2,2′-bipyridyl (bipy) to afford a substitution product [Ru2(RNNNR)2(CO)4(bipy)] which has been shown by X-ray diffraction methods to contain a pair of non-equivalent ruthenium atoms linked by a metal–metal bond (2.706A) and bridged by a 1,3-di-p-tolyltriazenide ligand and a pair of carbonyls. The co-ordination sphere of the first ruthenium atom is completed by a chelate triazenide ligand and a terminal carbonyl, that of the second ruthenium atom by a chelate bipy ligand and a terminal carbonyl.

Salicylaldehyde reacts with [RuH2(CO)(PPh3)3] in refluxing toluene to afford a ruthenium(II) salicylaldehydato(2–) complex which crystallised from CH2Cl2–light petroleum as a dichloromethane-solvated o-hydroxybenzyl alcohol adduct [[graphic omitted])(HOC6H4CH2OH)(CO)-(PPh3)2]·CH2Cl2, and from CH2Cl2–MeOH as the methanol- solvated methanol adduct [[graphic omitted])-(MeOH)(CO)(PPh3)2]·MeOH. Formation of the o-hydroxybenzyl alcohol adduct clearly implies the ruthenium-mediated reduction of the CHO group in salicylaldehyde. Carbon monoxide and pyridine react with [[graphic omitted])(MeOH)(CO)(PPh3)2]·MeOH to form [[graphic omitted])L(CO)(PPh3)2](L = CO or py respectively). The reaction of salicylaldehyde with [OsH2(CO)(PPh3)3] includes a carbonylation step and affords [[graphic omitted])(CO)2(PPh3)2]. Reactions of [RhH(PPh3)4] and mer-[IrH3(PPh3)3] with salicylaldehyde in boiling toluene afford [Rh(OC6H4CHO)(CO)(PPh3)2] and [[graphic omitted])H(CO)(PPh3)2] respectively. X-Ray diffraction studies on [[graphic omitted])(HOC6H4CH2OH)(CO)(PPh3)2]·CH2Cl2and[[graphic omitted])(MeOH)(CO)(PPh3)2]·MeOH establish the presence of O,C-chelated salicylaldehydate(2–) ligands in both cases and a monodentate o-hydroxybenzyl alcohol ligand in the former complex.

Amides, NH2COR (R = CF3, Ph), undergo metallation reactions to form mono- and bi-nuclear ruthenium(II) amido complexes, notably [Ru(NHCOCF3)2(H2O)(CO)(PPh3)2], the cyclometallated (N,C) benzamido derivative [Ph3P)(OC)[graphic omitted]6H4-o)(µ-NHCOPh)(µ-H)Ru(CO)(PPh3)2] and the quadruply bridged species [Ru2(µ-Cl)(µ-H)(µ-NHCOCF3)2(PPh3)4] all of which have been characterised by X-ray diffraction methods.

The ruthenium and osmium complexes [MH(Cl)(CO)(PPh3)3](M = Ru or Os) each react with benzotriazole (Hbta) in cold benzene to form a pair of geometrical isomers [MH(Cl)(Hbta)(CO)(PPh3)2](H trans to Hbta or Cl). The dihydrides [MH2(CO)(PPh3)3] react with excess of benzotriazole in boiling benzene (M = Ru) or toluene (M = Os) to afford products of the form [MH(bta ⋯ H–bta)(CO)(PPh3)2] containing a hydrogen-bonded benzotriazole–benzotriazolate pair co-ordinated as an NN′ chelate ligand. Similar chelate ligands are found in the products trans-[M(bta ⋯ H–bta)2(Hbta)(PPh3)] obtained from [RuH2(PPh3)4] and Hbta in boiling benzene, or from [MCl2(PPh3)3], Hbta, and triethylamine in boiling benzene (M = Ru) or toluene (M = Os). Isomeric forms of the complexes trans-[M(bta ⋯ H–bta)2(Hbta)(PPh3)] are thought to involve N2- or N3-co-ordinated Hbta ligands. Treatment of [IrCl(CO)(PPh3)2] with Hbta leads to reversible formation of the oxidative-addition product [IrH(Cl)(bta)(CO)(PPh3)2] in solution. The same reagents in the presence of NEt3 afford the known complex [Ir(bta)(CO)(PPh3)2]. Benzotriazole also reacts with mer-[IrH3(PPh3)3] to form [IrH2(bta ⋯ H–bta)(PPh3)2] and with [Pt(PPh3)4] to generate [Pt(bta)2(PPh3)2]. The nature of the hydrogen-bonded composite (bta ⋯ H–bta) ligand has been confirmed by an X-ray diffraction study on the osmium complex [OsH(bta ⋯ H–bta)(CO)(PPh3)2]. The crystals are triclinic, space group P, with a= 10.059(4), b= 11.876(1), c= 20.629(3)A, α= 74.57(1), β= 83.08(2), γ= 65.96(2)°, and Z= 2. A parallel series of complexes have been obtained using 5,6-dimethylbenzotriazole.

Reactions of 4,6-dimethylpyrimidine-2-thiol (Me 2 pymSH) and its oxidation product bis(4,6-dimethylpyrimidine-2-yl)disulphide (Me 2 pymSSpymMe 2 ) with a range of platinum metal complexes are described. The chlorohydrides [MHCl(CO)(PPh 3 ) 3 ] (M=Ru, Os) react with Me 2 pymSH in refluxing toluene to afford [RuCl(Me 2 pymS)(CO)(PPh 3 ) 2 ] and [OsH(Me 2 pymS)(CO)(PPh 3 ) 2 ] (two isomers). A similar reaction in cold benzene affords the substitution product [RuH(Cl)(Me 2 pymSH)(CO)(PPh 3 ) 2 ] (two isomers). Reaction of the precursors [MH 2 (CO)(PPh 3 ) 3 ] (MRu, Os) and [Ru(CO) 3 (PPh 3 ) 2 ] in boiling toluene afford [MH(Me 2 pymS)(CO)(PPh 3 ) 2 ] (two isomers) and [Ru(Me 2 pymS) 2 (CO)(PPh 3 )] (two isomers) respectively whilst the reaction of [Ru(CO) 3 (PPh 3 ) 2 ] with Me 2 pymSSpymMe 2 yields a mixture of [Ru(Me 2 pymS) 2 (CO) 2 (PPh 3 )] and [Ru(Me 2 pymS) 2 (CO)(PPh 3 )]. In the presence of the base (NEt 3 ) the dichlorides [MCl 2 (PPh 3 ) 3 ] (M=Ru, Os) react with Me 2 pymSH to afford the bis-chelates [M(Me 2 pymS) 2 (PPh 3 ) 2 ]. Reactions between Me 2 pymSH and the precursors [IrCl(CO)(PPh 3 ) 2 ] and [IrH(CO)(PPh 3 ) 3 ] at ambient temperature or below afford [IrH(Cl)(Me 2 pymS)(CO)(PPh 3 ) 2 ] and [IrH 2 (Me 2 pymS)(CO)(PPh 3 ) 2 ] respectively, the same ligand reacts with [RhCl(PPh 3 ) 3 ] and mer -[IrH 3 (PPh 3 ) 3 ] in refluxing benzene to afford [RhH(Cl)(Me 2 pymS)(PPh 3 ) 2 ], [Rh(Me 2 pymS) 3 (PPh 3 )], and [IrH 2 (Me 2 pymS)(PPh 3 ) 2 ]. The new complexes have been characterised by infrared and NMR [ 1 H, 31 P{ 1 H}] spectroscopy, and shown to contain monodentate (S-bonded) or chelate (N,S-bonded) Me 2 pymS ligands.

Trifluoroacetamide reacted with [RuCl2(PPh3)3]–NEt3 in boiling toluene to afford the binuclear species [Ru2(µ-Cl)(µ-H){µ-NHC(O)CF3}2(PPh3)4]1a(‘head-to-tail’ N,O-amidato bridged isomer). In contrast use of [RuH(Cl)(PPh3)3] as the ruthenium precursor led to formation of 1a as a mixture of ‘head-to-tail’ and ‘head-to-head’ isomers plus a small amount of another product 2a which is tentatively formulated as [Ru2(µ-H){µ-NHC(O)CF3}3(PPh3)4] with one N- and two N,O-bridging amidate ligands. Carbonylation of these products in boiling toluene yielded dicarbonyl species [Ru2(µ-Cl)(µ-H){µ-NHC(O)CF3}2(CO)2(PPh3)2]3a(‘head-to-tail’ and ‘head-to-head’ isomers) plus a trace of [Ru2(µ-H){µ-NHC(O)CF3}3(CO)2(PPh3)2]4a. Under similar conditions trifluoroacetamide reacted with [RuH2(CO)(PPh3)3], [Ru(CO)3(PPh3)2], [OsH2(CO)(PPh3)3] and mer-[IrH3(PPh3)3] to yield the mononuclear products [Ru{NHC(O)CF3}2(CO)(H2O)(PPh3)2]5a, [Ru{NHC(O)CF3}2(CO)2(PPh3)2]6a, [OsH{NHC(O)CF3}(CO)(PPh3)3]7a and [IrH2{NHC(O)CF3}(PPh3)3]8a respectively, all of which contain monodentate N-bonded trifluoroacetamidate ligands. Pentafluoropropionamide and pentafluorobenzamide yielded analogous products 1b, 2b, 3b and 8b, and 1c respectively. The crystal structure of [Ru2(µ-Cl)(µ-H){µ-NHC(O)C2F5}2(PPh3)4]1b has been determined. All other products were characterised by infrared and NMR spectroscopy.

Trifluoroacetamidine, NHC(CF3)–NH2, underwent a condensation reaction in the presence of certain platinum metal hydrides in boiling toluene to liberate ammonia and form complexes containing the N,N′-chelating 1,1,1,5,5,5-hexafluoro-3-azapentane-2,4-diiminate ligand NHC(CF3)NC(CF3)NH. Complexes prepared in this manner were [[graphic omitted]H}H(CO)(PPh3)2, [[graphic omitted]H}Cl(CO)(PPh3)2, [[graphic omitted]H}2(PPh3)2(M = Ru or Os) and [[graphic omitted]H}H2(PPh3)2. Under similar conditions [Ru(O2CCF3)2(CO)(PPh3)2reacted to afford the complex [[graphic omitted]H}(O2CCF3)(CO)(PPh3)2 in which intramolecular hydrogen bonding between the non-co-ordinated oxygen of the monodentate trifluoroacetate ligand and the adjacent NH moiety has been detected. An X-ray crystallographic study performed on [[graphic omitted]H}H(CO)(PPh3)2has confirmed an octahedral ruthenium(II) structure with trans-phosphine ligands and a chelating NHC(CF3)NC(CF3)NH– moiety.

Benzamide reacts with [RuH2(CO)(PPh3)3] and [RuH(Cl)(PPh3)3] or [RuCl2(PPh3)3]–NEt3 in boiling toluene to afford the amidato products [(Ph3P)(OC) [graphic omitted]6H4}{µ-NHC(O)Ph}(µ-H)Ru(CO)(PPh3)2]1a and [Ru2(µ-Cl)(µ-H){µ-NHC(O)Ph}2(PPh3)4]2a respectively as orange or red air-stable crystals. Parallel reactions with o-, m- and p-toluamides yield analogous products 1b–1d and 2b–2d. Carbonylation of [Ru2(µ-Cl)(µ-H){µ-NHC(O)Ph}2(PPh3)4] in boiling toluene affords the dicarbonyl [Ru2(µ-Cl)(µ-H){µ-NHC(O)Ph}2(CO)2(PPh3)2]3. Benzamide also reacts with [OsH2(CO)(PPh3)3] to yield the bis(benzamidato) complex [Os{NHC(O)Ph}2(CO)2(PPh3)2]4. A crystallographic study of 1a established a binuclear structure bridged by hydride, benzamidate(1–) and benzamidate(2–) ligands.

The complexes (MH(O2CCF3) (CO) (PPh3)2] and (M(O2CCF3)2(CO)(PPh3)2] (M = Ru or Os) react with terminal and internal acetylenes to afford oligomerisation and hydrogenation products, respectively, together with vinylic complexes, including the ruthenium species [Ru(C4HPh2)(O2CCF3)(CO) (PPh3)2], which has been shown by x-ray diffraction methods to contain a 1,4-diphenylbut-1-en-3-yn-2-yl ligand.

Ruthenium and osmium hydridonitrosyl complexes, [MH(NO)(PPh3)3], react with perfluorocarboxylic acids RCO2H (R = CF3 or C2F5) to afford the products [Ru(O2CR)3(NO)(PPh3)2] and [OsH(O2CR)2(NO)(PPh3)2] respectively. The reaction intermediates [RuH(O2CR)2(NO)(PPh3)2] and [OsH2(NO)(PPh3)3]+ have been detected in solution by 1H and 31P-{1H} n.m.r.; the latter species has been isolated and characterised as the tetraphenylborate salt. The ruthenium dinitrosyl complex [Ru(NO)2(PPh3)2] reacts with the acids RCO2H in boiling toluene or 2-methoxyethanol to afford the products [Ru(O2CR)3(NO)(PPh3)2]. The corresponding osmium complex [Os(NO)2(PPh3)2] reacts with the same acids in boiling 2-methoxyethanol and boiling toluene to yield the hydrides [OsH(O2CR)2(NO)(PPh3)2] and the novel hydroximate derivatives [[graphic omitted]R}(O2CR)(NO)(PPh3)2] respectively. Possible mechanisms for these reactions are discussed. The X-ray crystal structure of [[graphic omitted]CF3}(O2CCF3)(NO)(PPh3)2]·CH2Cl2 has been determined. The crystals are triclinic, space group P, with a= 12.709(3), b= 22.694(8), c= 9.662(3)A, α= 118.28(3), β= 113.59(3), γ= 59.66(4)°, and Z= 2. The structure has been refined to R(F)= 0.051 and R′(F)= 0.049 for 4 730 observed reflections. The complex contains six-co-ordinated osmium(II) bound to a chelate O,O′-trifluoroacetohydroximate(2–) ligand, a unidentate trifluoroacetate ligand, a linear nitrosyl group, and a pair of mutually cis triphenylphosphine ligands.

The hydrides [MH(O2CCF3)(CO)(PPh3)2] (M = Ru or Os) react with disubstituted acetylenes PhCCPh and PhCCMe to afford vinylic products [M{C(Ph)CHPh}(O2CCF3)(CO)(PPh3)2] and [M{C(Ph)CHMe}(O2CCF3)(CO) (PPh3)2]/[M{C(Me)CHPh}(O2CCF3)(CO)(PPh3)2] respectively. Acidolysis of these products with trifluoroacetic acid in cold ethanol liberates cis-stilbene and cis-PhHCCHMe respectively thus establishing the cis-stereochemistry of the vinylic ligands. The complexes [M(O2CCF3)2(CO)(PPh3)2] formed during the acidolysis step undergo facile alcoholysis followed by β-elimination of aldehyde to regenerate the parent hydrides [MH(O2CCF3)(CO)(PPh3)2] and thereby complete a catalytic cycle for the transfer hydrogenation of acetylenes. The molecular structure of the methanol-adduct intermediate, [Ru(O2CCF3)2(MeOH)(CO)(PPh3)2] has been determined by X-ray methods and shows that the coordinated methanol is involved in H-bonding with the monodentate trifluoroacetate ligand [MEO-H---OC(O)CF3; O...O = 2.54 A]. The hydrides [MH(O2CCF3)(CO) (PPh3)2]react with 1,4-diphenylbutadiyne to afford the complexes [M{C(CCPh)CHPh} (O2CCF3)(CO)(PPh3)2]. The ruthenium product, which has also been obtained by treatment of [RuH(O2CCF3)(CO)(PPh3)2] with phenylacetylene, has been shown by X-ray diffraction methods to contain a 1,4-diphenylbut-1-en-3-yn-2-yl ligand. The osmium complexes [Os(O2CCF3)2(CO)(PPh3)2], [OsH(O2CCF3)(CO)(PPh3)2] and [Os{C(CCPh)CHPh}(O2CCF3)(CO)(PPh3)2] all serve as catalysts for the oligomerisation of phenylacetylene. Acetylene reacts with [Ru(O2CCF3)2(CO)(PPh3)2] in ethanol to afford the vinyl complex [Ru(CHCH2)(O2CCF3)(CO)(PPh3)2].

The chelating diphosphines Ph2P(CH2)nPPh2(n= 1–3) react with binuclear carboxylato complexes [Ru2(O2CR)4Cl](R = Me, Et, or Ph) in cold or refluxing benzene to yield products trans-[Ru(O2CR)2{Ph2P(CH2)nPPh2}2] and cis-[Ru(O2CR)2{Ph2P(CH2)nPPh2}2] respectively, both of which are readily converted to the tetraphenylborate salts [Ru(O2CR){Ph2P(CH2)nPPh2}2]BPh4. Attempts to obtain similar products using samples of [Ru2(O2CR)4Cl](R = CF3 or But), prepared from the corresponding acetate complex by treatment with the appropriate carboxylic acids under vigorous conditions, gave mixtures indicative of incomplete carboxylato exchange. The trans complexes [Ru(O2CR)2(Ph2PCH2PPh2)2] react with NaBH4 and CO to afford cis- and trans-[RuH2(Ph2PCH2PPh2)2] and cis,cis,trans-[ Ru(O2CR)2(CO)2(Ph2PCH2PPh2)2] respectively. The latter species react with NaBH4 to yield cis- and trans-[RuH2(CO)(Ph2PCH2PPh2)2]. Several of these products contain pendant Ph2PCH2PPh2 ligands. The corresponding complexes containing Ph2P(CH2)2PPh2 failed to carbonylate even under vigorous conditions. The relationship between chelate ring size and 31P n.m.r. parameters for some of these complexes is discussed. Confirmation that the cations contained in the tetraphenylborate salts are mononuclear and not, as previously suggested elsewhere, binuclear has been provided by an X-ray diffraction study of one such salt [Ru(O2CMe)(Ph2PCH2PPh2)2]BPh4. The crystals are triclinic, space group P(no. 2), with a= 14.693(5), b= 18.821(4), c= 11.807(3)A, α= 95.39(2), β= 108.03(2), γ= 92.43(2)°, and Z= 2 at 144(2) K. The complex contains tris(chelate)ruthenium(II) cations with bidentate acetate and bis(diphenylphosphino)methane ligands together with tetraphenylborate anions.

The ruthenium(I) triazenido complexes [Ru(ArNNNAr)(C0)3]2 (Ar = p-C6H4Me or p-C6H4Cl) have been prepared by heating RU3(CO)12 with free triazene in benzene under a carbon monoxide atmosphere, and by heating [Ru(O2CMe)(CO)2]n with free triazene and triethylamine in acetonitrile under carbon monoxide. Reactions of the diruthenium(I/I) triazenido complexes with PPh3, P(OME)3 or ArNNNHAr (Ar =p-C6H4Cl) afford axial substitution products of the general form [Ru(ArNNNAr)(CO)2L]2. However, with ArNNNHAr (Ar = p-C6H4Me) cleavage of triazene to generate axial p-toluidine ligands occurs. The structure of the p-toluidine adduct, [Ru(ArNNNAr)(CO)2(NH2Ar)]2 has been determined by X-ray diffraction methods. The compound crystallizes in space group P 1 with a = 11.350(1), b = 20.582(4), c= 10.371(5) A, α = 100.75(4), β = 104.30(3), γ = 84.40(1)°; U = 2303.89 A3 and Z = 2.

The reactions of PriNCNPri with the complexes [RuH(X)(CO)(PPh3)3](X = Cl or Br) in boiling benzene involve insertion of the carbodi-imide moiety into the Ru–H bond and concomitant dehydrogenation of an isopropyl group to yield the derivatives [RuX{CH2C(Me)N CH NCHMe2}(CO)(PPh3)2]. A single-crystal X-ray diffraction study of the chloro-complex (X = Cl) has confirmed the presence of an N-isopropenyl-N′-isopropylformamidinate ligand in which the isopropenyl skeleton is essentially coplanar with, and conjugated to, the formamidinate group. The crystals are monoclinic, space group P21/a, with a= 17.836(2), b= 18.443(3), c= 12.607(1)A, β= 104.59(3)°, and Z= 4. The structure has been solved via the heavy-atom method and refined by least squares using 4 381 observed [I > 1.5σ(l)] diffractometer intensities to a final R of 0.086. The octahedral molecule comprises two trans phosphines [Ru–P 2.383(4) and 2.400(4)A], a chelating formamidinate ligand [Ru–N 2.048(10) and 2.242(10)A], a carbonyl group [Ru–C 1.805(12)A], and a chlorine atom [Ru–Cl 2.434(4)A], the latter being trans to the more strongly bound nitrogen atom. The complex [OsH2(CO)(PPh3)3] reacts with PriNCNPri to afford the intermediate product [OsH(Me2HCN CH NCHMe2)(CO)(PPh3)2] which, on further heating, dehydrogenates to [OsH{CH2C(Me)N CH NCHMe2}(CO)(PPh3)2] in good yield.

The complexes [MHCl(CO)(PPh3)3] (M = Ru or Os) readily undergo substitution at the site trans to the hydride ligand to afford phosphinite-, phosphonite-, or phosphite-containing products [MHCI(CO)(PPh3)2L] [L = P(OR)Ph2, P(OR)2Ph or P(OR)3 respectively; R = Me or Et]. The ruthenium complexes alone undergo further substitution to afford complex cations [RuH(CO)(PPh3)nL4−n]+ [n = 2, L = P(OMe)3; n = 1, L = P(OR)3; n = 0, L = P(OR)2Ph or P(OR)Ph2] which were isolated and characterised as their tetraphenylborate salts. Synthesis of the cationic complexes [IrHL5][BPh4]2 [L = P(OR)3, R = Me or Et] is also reported. Stereochemical assignments based on NMR data are given, and second order 31P and high field 1H NMR patterns are analysed.

The precursors MH 2 (CO)(PPh 3 ) 3 (M = Ru or Os), Ru(CO) 3 (PPh 3 ) 2 /OsH 2 (CO) 2 (PPh 3 ) 2 and IrH(CO)(PPh 3 ) 3 react with 1,3,4-thiadiazole-2,5-dithiol (tddtH 2 ) in boilig toluene to afford the 1,3,4-thiadiazole-2,5-dithiolato (tddtH) complexes M(tddtH) 2 (CO)(PPh 3 ) 2 , M(tddtH) 2 (CO) 2 (PPh 3 ) 2 and IrH(tddtH) 2 (CO)(PPh 3 ) 2 respectively. The molecular structure of the ruthenium complex Ru(tddtH) 2 (CO)(PPh 3 ) 2 has been determined by X-ray diffraction methods, the crystals are triclinic space group P 1 , Z = 2, unit cell dimensions are a = 13.051(3), b = 16.404(7), c = 16.500(5) A, α = 119.60(2), β = 91.46(2), γ = 104.21(3)°, ( V = 2932.0(16) A 3 . The structure contains octahedral ruthenium(II) with mon-dentate (S-coordinated) and bi-dentate (N,S-coordinated) tddtH ligands, a carbonyl group and a trans pair of triphenylphosphine ligands. The complexes M(tddtH) 2 (CO)(PPh 3 ) 2 and the closely related ruthenium 5-methyl-1,3,4-thiadiazole 2-thiolato complex Ru(mtdt) 2 (CO)(PPh 3 ) 2 have been shown by 1 H NMR to display dynamic interchange of mono- and bi-dentate thiolate ligands. Some rhodium(I), palladium(0) and platinum(0) complexes of tddtH 2 are tentatively reformulated.

Nitrato complexes of the platinum group metals have been prepared by treating selected hydridic or zero oxidation state precursors with nitric acid, neat or in organic media. Products obtained in this manner include [M(NO,),(CO)(PPh,),], [.M(NOJ2(CO)2(PPh3),1 (M = Ru or Os), [M’(NO,),(PPh,),], and [M’(NO,),(NO)(PPh,),] (M’ = Rh or Ir). The species [M(N03),(CO)(PPh,)2] undergo carbonylation to yield the dicarbonyls [M(N0,)2(CO)2(PPh3)2] and alcoholysis followed by P-elimination to form the hydrides [MH(NO,)(CO)(PPh,),]. The latter products are readily carbonylated to afford the species [MH(NO,)(CO),(PPh,),]. The new complexes have been characterized and their stereochemistry has been assigned by reference to spectroscopic data. The complex “Rh(N03)(NO)2(0PPh3)2” has been reformulated as [Rh(N03)2(NO)(PPh,)2]. However, one product obtained on treating [RuH,(CO)(PPh,),] with nitric acid has been tentatively identified as a triphenylphosphine oxide derivative [Ru(N0,),(NO)(OPPh3)(PPh,)]. The ability of [RU(NO,)~(CO)(PP~,)~] to catalyze the dehydrogenation of primary and secondary alcohols is noted.

1,3-Diaryltriazenes, ArN = NNHAr (Ar = Ph, p-MeC6H4 and p-MeOC6H4) react with platinum metal halide complexes in the presence of triethylamine to afford products containing mono- or bi-dentate (chelate or bridging) 1,3-diaryltriazenide ligands. Complexes prepared in this manner include derivatives of ruthenium(II), 2(PPh3)2] and (CO)(PPh3)2]; rhodium(I), 2], (C8H12)(PPh3)] and (CO)(PPh3)2]; palladium(II) L2] (X = Cl, L = PPh3, PEt3, AsPh3, PMePh2; X = Br, L = PMePh2; X = I, L = PMe2Ph), and 2(PMe2Ph)2]; and platinum(II(, [PtCl L2] (L = PPh3, PEt3, and PEt2Ph; L = C8H12). The intramolecular N(1)–N(3) exchange process: displayed by the monodentate 1,3-diaryltriazenido derivatives of rhodium(I), palladium(II) and platinum(II) have been studied by dynamic proton NMR spectroscopy, and thermodynamic parameters of activation have been determined. ΔH≠ values were found to lie within the range ca. 32–44 kJ mol−1 for the palladium(II) and platinum(II) complexes, ΔS≠ values are all negative.

The ruthenium(II) and osmium(II) complexes MCl 2 (PPh 3 ) 3 , undergo oxidative substitution reactions with β-diketones under aerobic conditions in warm benzene to afford ruthenium(III) and osmium(III) β-diketonate complexes, MCl 2 (β-diketonate)(PPh 3 ) 2 . Generally these products appear to adopt the less sterically hindered trans -phosphine stereochemistry, but one example, RuCl 2 {CF 3 C(O)CHC(O)CF 3 }(PPh 3 ) 2 , deposits from hot and cold reactions as yellow ( trans -phosphines) and red ( cis -phosphines) isomers, respectively.

Reactions of 4,6-dimethylpyrimidine-2-thiol (Me 2 pymSH) and its oxidation product bis(4,6-dimethylpyrimidine-2-yl)disulphide (Me 2 pymSSpymMe 2 ) with a range of platinum metal complexes are described. The chlorohydrides [MHCl(CO)(PPh 3 ) 3 ] (M=Ru, Os) react with Me 2 pymSH in refluxing toluene to afford [RuCl(Me 2 pymS)(CO)(PPh 3 ) 2 ] and [OsH(Me 2 pymS)(CO)(PPh 3 ) 2 ] (two isomers). A similar reaction in cold benzene affords the substitution product [RuH(Cl)(Me 2 pymSH)(CO)(PPh 3 ) 2 ] (two isomers). Reaction of the precursors [MH 2 (CO)(PPh 3 ) 3 ] (MRu, Os) and [Ru(CO) 3 (PPh 3 ) 2 ] in boiling toluene afford [MH(Me 2 pymS)(CO)(PPh 3 ) 2 ] (two isomers) and [Ru(Me 2 pymS) 2 (CO)(PPh 3 )] (two isomers) respectively whilst the reaction of [Ru(CO) 3 (PPh 3 ) 2 ] with Me 2 pymSSpymMe 2 yields a mixture of [Ru(Me 2 pymS) 2 (CO) 2 (PPh 3 )] and [Ru(Me 2 pymS) 2 (CO)(PPh 3 )]. In the presence of the base (NEt 3 ) the dichlorides [MCl 2 (PPh 3 ) 3 ] (M=Ru, Os) react with Me 2 pymSH to afford the bis-chelates [M(Me 2 pymS) 2 (PPh 3 ) 2 ]. Reactions between Me 2 pymSH and the precursors [IrCl(CO)(PPh 3 ) 2 ] and [IrH(CO)(PPh 3 ) 3 ] at ambient temperature or below afford [IrH(Cl)(Me 2 pymS)(CO)(PPh 3 ) 2 ] and [IrH 2 (Me 2 pymS)(CO)(PPh 3 ) 2 ] respectively, the same ligand reacts with [RhCl(PPh 3 ) 3 ] and mer -[IrH 3 (PPh 3 ) 3 ] in refluxing benzene to afford [RhH(Cl)(Me 2 pymS)(PPh 3 ) 2 ], [Rh(Me 2 pymS) 3 (PPh 3 )], and [IrH 2 (Me 2 pymS)(PPh 3 ) 2 ]. The new complexes have been characterised by infrared and NMR [ 1 H, 31 P{ 1 H}] spectroscopy, and shown to contain monodentate (S-bonded) or chelate (N,S-bonded) Me 2 pymS ligands.

The title compound, prepared by heating [RuHCl(CO)(PPh 3 ) 3 ] with di- isop ropylcarbodiimide (Pr i N=C=NPr i ) in boiling benzene, has been shown by 1 H n.m.r. and X-ray diffraction methods to contain the N- isop ropenyl-N′- isop ropylformamidinate ligand generated by insertion of the carbodiimide moiety into the Ru H bond and the concomitant loss of molecular hydrogen from one of the isop ropyl groups.

The synthesis and characterization of new benzotriazole (btaH) complexes M(btaHbta)2(btaH)(PPh3) (N2 and N3-btaH linkage isomers), M(btaHbta)H(CO)(PPh3)2 (M = Ru or Os) and IrH2(btaHbta)(PPh3)2, in which the H-bonded benzotriazolate anion—benzotriazole pair (btaHbta)′ functions as a novel N,N′-chelate ligand, are reported. The stereochemistry of the osmium complex Os(btaHbta)H(CO)(PPh3)2 and the nature of the btaHbta moiety therein have been confirmed by an X-ray crystal structure determination.

Ruthenium and osmium precursors [MH(Cl)(CO)(PPh3)3], [MH2(CO)(PPh3)3], [Ru(CO)3(PPh3)2], [OsH2(CO)2(PPh3)2], [RuH2(PPh3)4], and [OsH4(PPh3)3] react with pyridine-2-thiol (pySH) or dipyridyl-2,2′-disulphide (pySSpy) in boiling benzene or toluene to afford a range of pyridine-2-thiolate complexes including [MCl(pyS)(CO)(PPh3)2], (2 isomers), [M(pyS)2(CO)2(PPh3)], [M(pyS)2(CO)(PPh3)], and [M(pyS)2(PPh3)2] in which the pyridine-2-thiolate ligands are bound in monodentate (S-bonded) or bidentate (N,S-chelated) mode. Similar products are obtained from [RuCl2(PPh3)3] and [RuCl2(CO)2(PPh3)2] in the presence of triethylamine and pyridine-2-thiol. The new complexes have been characterised by i.r. and n.m.r. (31P-{1H} and 1H) spectroscopy; reaction pathways are discussed. The X-ray crystal structures of [Ru(pyS)2(CO)2(PPh3)] and [Ru(pyS)2(CO)(PPh3)] have been determined. The dicarbonyl [Ru(pyS)2(CO)2(PPh3)], which undergoes facile conversion to [Ru(pyS)2(CO)(PPh3)], displays structural evidence of incipient attack by the non-co-ordinated N atom of the monodentate pyridine-2-thiolate ligand on a carbonyl group [N ⋯ C 2.782(7)A]. Crystals of [Ru(pyS)2(CO)2(PPh3)] are monoclinic, space group P21/c, with a= 11.307(2), b= 11,083(3), c= 24.090(5)A, β= 109.47(2)°, and Z= 4. The structure, which has been refined to R= 0.045 for 4 375 observed reflections, consists of highly distorted octahedral ruthenium(II) molecules with monodentate (S-bonded) and bidentate (N,Sbonded) pyridine-2-thiolate ligands, a cis pair of carbonyl groups, and a triphenylphosphine ligand trans to the S-bonded pyridine-2-thiolate. Crystals of [Ru(pyS)2(CO)(PPh3)] are triclinic, space group P, with a= 10.317(3), b= 11.749(3), c= 12.517(3)A, α= 67.65(2), β= 70.55(2)γ= 86.43(2)°, and Z= 2. The structure, which has been refined to R= 0.040 for 12 196 observed reflections consists of highly distorted octahedral ruthenium(II) molecules with a cis pair of bidentate (N,S-bonded) pyridine-2-thiolate ligands (trans S atoms), a carbonyl group, and a triphenylphosphine ligand.