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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.

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.

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.

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.

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 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 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.

Sulphonic acids RSO3H (R = CF3, CH3, or C6H4CH3-p) react with mer-[IrH3(PPh3)3], [IrCl(CO)(PPh3)2], and [IrH (CO)(PPh3)3] to afford the products [IrH2(O3SR)(PPh3)3], [IrH(Cl)(O3SR)(CO)(PPh3)2], and [lrH2(CO)(PPh3)3][O3SR] respectively. Under more vigorous conditions the last reaction yields the bis(sulphonate) complexes [IrH(O3SR)2(CO)(PPh3)2]. The lability of the monodentate sulphonate ligands has been demonstrated by the substitution reactions of [lrH2(O3SR)(PPh3)3] with a variety of neutral donor ligands. Products readily obtained in this manner include [IrH2(CH3CN)(PPh3)3][O3SR], [IrH2L2(PPh3)2][O3SR][L = pyridine, 4- methylpyridine, or P(OPh)3; L2= 2,2′-bipyridyl, 1, 10-phenanthroline, ethylenediamine, or o-NH2-C6H4NH2], and trans-[IrH2(Ph2PCH2PPh2)2][O3SR]. Carbonylation of [IrH2(O3SCF3)(PPh3)3] affords the tricarbonyl salt [Ir(CO)3(PPh3)2][O3SCF3] whereas under similar conditions the precursors [IrH2(O3SR)(PPh3)3](R = CH3 or C6H4CH3-p) yield the dihydride salts [IrH2(CO)(PPh3)3][O3SR]. Many of the complexes isolated were solvated by H-bonded molecules of sulphonic acids. Stereochemical assignments based on 1H, 19F, and 31P n.m.r. data are given for all the new products reported.

The rhodium complex [Rh(NO)(PPh3)3] reacts with perfluorocarboxylic acids, RCO2H, in the presence of dioxygen to afford emerald green complexes [Rh(O2CR)2(NO)(PPh3)2](R = CF3, C2F3, or C6F5) in good yield. In contrast, the corresponding iridium precursor, [Ir(NO)(PPh3)3] reacts with the same acids under aerobic or anaerobic conditions to yield brown complexes [Ir(O2CR)2(NO)(PPh3)2]. The trifluoroacetate derivatives have been examined by X-ray diffraction methods and shown to possess dissimilar structures. Crystals of the rhodium complex are monoclinic, space group Cc, with a= 12.593(2), b= 15.466(3), c= 20.479(3)A, β= 100.03(4)°, and Z= 4. The structure, which has been refined to R= 0.06 for 2 918 observed reflections, consists of tetragonal-pyramidal molecules with angular apical nitrosyl ligands and trans phosphine ligands. Crystals of the iridium complex (solvated with one molecule of acetone) are orthorhombic, space group Pbcn, with a= 19.171(2), b= 22.684(3), c= 20.169(3)A, and Z= 8. The structure, which has been refined to R= 0.081 for 3 791 observed reflections, consists of trigonal-bipyramidal molecules with linear equatorial nitrosyl groups and axial trans phosphine ligands. The angle subtended at the iridium by the co-ordinated oxygen atoms of the unidentate trifluoroacetate ligands is remarkably small [75.0(6)°]. Preliminary calculations performed using a steric energy calculation computer program, EENY2, suggest that in each case the structure adopted corresponds to a stereochemical energy minimum.

Sulphonic acids RSO3H (R = CH3, CF3, or C6H4CH3-p) react with the precursors [MH2(CO)(PPh3)3](M = Ru or Os) and [Ru(CO)3(PPh3)2] or [OsH2(CO)2(PPh3)2] in refluxing benzene or toluene to afford the complexes [M(O3SR)2(H2O)(CO)(PPh3)2] and [M(O3SR)2(CO)2(PPh3)2] respectively. The precursors [RuH2(PPh3)4] and [OsH4(PPh3)3] react with sulphonic acids in refluxing benzene to give the η6-benzene complexes [MH(η6-C6H6)(PPh3)2][O3SR]. However a similar reaction in refluxing ethanol yielded [OsH3(PPh3)4][O3SCF3]. The complexes [Ru(O3SR)2(H2O)(CO)(PPh3)2] have been shown by variable-temperature 1H and 31P-{1H} n.m.r. spectroscopy to be fluxional in solution. The solid-state structure of one example, [Ru(O3SC6H4CH3-p)2(H2O)(CO)(PPh3)2] has been determined by X-ray diffraction methods. The crystals are monoclinic, space group P21/n, with a= 24.382(5), b= 18.075(4), c= 10.729(2)A, β= 99.03(2)°, and Z= 4. The octahedral ruthenium(II) complex contains monodentate sulphonate ligands (trans to PPh3 and CO) and an aqua ligand (trans to PPh3) with strong hydrogen-bonding interactions between the H atoms of the H2O and the non-co-ordinated oxygen atoms of the sulphonate ligands. The molecular structure is very similar to that previously reported for the alcohol dehydrogenation catalyst [Ru(O2CCF3)2(CH3OH)(CO)(PPh3)2].

Osmium triphenylphosphine complexes, [OsH4(PPh3)3], [OsH2(CO)(PPh3)3], and [OsHCl(CO)(PPh3)3] react with triphenyl phosphite in boiling organic solvents to yield triphenyl phosphite derivatives which subsequently undergo ortho-metallation. Products isolated and characterised include the substituted derivatives [OsHCl(CO)(PPh3)2(p)] and [OsHCl(CO)(PPh3)(p)2], the metallated species [OsCl(pc)(CO)(PPh3)(p)], [OsCl(pc)(CO)(p)2], [OsH(PC)(CO)(PPh3)(p)], and [OsH(pc)(CO)(p)2], and the dimetallated complexes [Os(pc)2(p)2] and [Os(pc)2(CO)(p)][(P)= P(OPh)3; (pc)=(PhO)2P(OC6H4)].

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.

Perfluorocarboxylic acids, RFCO2H (RF= CF3, C2F5, or C6F5), react with hydrido(triphenylphoshine) or low-oxidation-state triphenylphosphine complexes of the platinum-group metals to yield a wide range of perfluorocarboxylato-derivatives. Products which have been prepared in this manner include [RuCl(OCOCF3)(CO)(PPh3)2], [Ru(OCORF)2(CO)(PPh3)2], [Ru(OCORF)2(CO)2(PPh3)2], [RuH(OCOCF3)(PPh3)3], [OsCl(OCORF)(CO)(PPh3)3], [OsH(OCORF)(CO)(PPh3)3], [Os(OCORF)2(CO)(PPh3)2], [OsH(OCORF)(CO)2(PPh3)2], [Os(OCORF)2(CO)2(PPh3)2], [OsH(OCOCF3)(PPh3)3], [Rh(OCORF)(PPh3)3], [Rh(OCORF)(CO)(PPh3)2], [IrH(OCORF)2(CO)(PPh3)2], and [Ir(H)2(OCORF)(PPh3)3]. The new complexes have been characterised and, where possible, their stereochemistry has been determined by i.r. and n.m.r. spectroscopy. The occurrence of a rapid intramolecular exchange between uni- and bi-dentate perfluorocarboxylate ligands in the complexes [M(OCORF)2(CO)(PPh3)2](M = Ru or Os) has been established by observation of temperature-dependent 19F n.m.r. spectra for the trifluoroacetate derivatives. Mechanisms involving oxidative addition of perfluorocarboxylic acids to the precursors, and subsequent reductive elimination of dihydrogen, are proposed for the reactions discussed. The tendency for unidentate perfluorocarboxylate ligands situated trans to strong σ-donor ligands to undergo alcoholysis is reported.

The role of dioxygen in the conversion of the nitrosyls [M(NO)(PPh3)3](M = Rh or Ir) to the nitrosyl trifluoroacetates [M (O2CCF3)2(NO)(PPh3)2] by trifluoroacetic acid, CF3CO2H, under aerobic conditions has been investigated by n.m.r. spectroscopy and gas uptake/evolution measurements. The rhodium reaction has been shown to proceed rapidly to completion in the presence of air with the consumption of a stoicheiometric amount of dioxygen (one mole per mole of complex) but occur only slowly and inefficiently under anaerobic conditions. In contrast, the corresponding iridium reaction occurs quite readily under anaerobic conditions. Mechanisms are proposed for these reactions and a similar dioxygen dependence in the reaction of [Pt(PPh3)4] with acetic acid is discussed.

New dithiocarbamato- and O-alkyl dithiocarbonato-derivatives, [M(S–S)2(PPh3)2], [M(S–S)2(CO)(PPh3)], [MH(S–S)(CO)(PPh3)2](M = Ru or Os; S–S = R2NCS2– or ROCS2–; R = Me or Et), [OsCl(S2CNR2)(CO)(PPh3)2], and [IrH2(S–S)(PPh3)2], have been prepared by treating the appropriate chloro- orcarboxylato-complexes with sodium salts of the ligand. In several instances, hydride ligands, present in the parent complex, are also replaced by S–S groups. Tetramethylthiuram disulphide reacts with [IrCl(CO)(PPh3)2], [RuH2(PPh3)4], and [RuH2(CO)(PPh3)3] or [RuHCl(CO)(PPh3)3] to afford the complexes [Ir(S2CNMe2)2(CO)(PPh3)]Cl, [Ru(S2-CNMe2)2(PPh3)2], and [Ru(S2CNMe2)2(CO)(PPh3)] respectively. Structural and stereochemical assignments based on n.m.r. and i.r. spectroscopic data for the R2NCS2– and ROCS2– complexes confirm the expected substantial barrier to rotation about the S2C–NR2 bond in the former, but reveal no evidence of a comparable barrier to rotation about the S2C–OR bond in the latter.

Reactions between metal halides, metal carbonyl halides, or metal olefin halides and dialkyl phenylphosphonite, P(OR)2Ph, or alkyl diphenylphosphinite, P(OR)Ph2, ligands (R = Me, Et) performed in polar or aromatic solvents afford a general route to an extensive series of uncharged complexes. Compounds isolated in this way include RuCl2(CO)2L2, RuCl2(CO)L3, OsCl2(CO)2L2, IrHCl2L3, cis-PdCl2L2, cis-PtCl2L2, cis-PtBr2L2[L = P(OR)Ph2, P(OR)2Ph; R = Me, Et], AgCl[P(OEt)Ph2]2, AgClL′[L′= P(OR)2Ph, P(OMe)Ph2], and AuCl[P(OEt)Ph2]. 1H and 31P N.m.r. spectra are presented and discussed.

1,3-Diaryltriazenes, ArN:N·NHAr, react with hydrido or low-oxidation state phosphine complexes of the platinum metals to afford products containing monodentate or chelate 1,3-diaryltriazenido (ArNNNAr–) ligands. Highly coloured, air stable, crystalline products synthesised in this manner include 1,3-diaryltriazenido derivatives of ruthenium :Ru(ArNNNAr)2(PPh3)2, RuH(ArNNNAr)(CO)(PPh3)2, RuCl(ArNNNAr)(CO)(PPh3)2; osmium: Os-(ArNNNAr)2(PPh3)2, OsH(ArNNNAr)(CO)(PPh3)2, OsH3(ArNNNAr)(PPh3)2; rhodium: RhH2(ArNNNAr)(PPh3)2, Rh(ArNNNAr)3, RhCl(ArNNNAr)2(PPh3), Rh(NO)(ArNNNAr)2(PPh3), Rh(ArNNNAr)(CO)(PPh3)2[Rh(Ph2PCH2CH2PPh2)2][ArNNNAr]; iridium: IrH2(ArNNNAr)(PPh3)2, IrHCl(ArNNNAr)(PPh3)2; palladium; cis- and trans-Pd(ArNNNAr)2(PPh3)2; and platinum: cis- and trans-Pt(ArNNNAr)2(PPh3)2, Pt(ArNNNAr)2[Ph2P(CH2)nPPh2](n= 2–4), and PtCl(ArNNNAr)(PR3)2(R = Et or Ph). The new complexes are characterised, and their stereochemistry determined, by i.r. and n.m.r. spectroscopy.

The complexes [Ru(CO)(Cl)H(PPh3)3], [Ru(CO)H2(PPh3)3], [Ru(CO)3(PPh3)2], and [RuH2(PPh3)4] react with triphenyl phosphite in hydrocarbon solvents to yield triphenyl phosphite derivatives which subsequently undergo ortho-metallation. Products which have been isolated and/or characterised include the substituted species [Ru(CO)(Cl)H(PPh3)2{P(OPh)3}] and [Ru(CO)(Cl)H(PPh3){P(OPh)3}2], and the metallated derivatives [Ru(CO)(Cl){P(OPh)3}2(pc)], [Ru(CO)H(PPh3){P(OPh)3}(pc)], [Ru(CO)H{P(OPh)3}2(pc)], and [Ru{P-(OPh)3}2(pc)2][pc = P(OPh)2(OC6H4)]. Attempts to reverse the metallation process by addition of hydrogen chloride or hydrogen to [Ru{P(OPh)3}2(pc)2] under mild conditions have been usuccessful; however, this complex undergoes demetallation in the presence of perfluorocarboxylic acids, RFCO2H, to yield the species trans-[Ru(O2CRF)2{P(OPh)3}4]·RFCO2H (RF= CF3 or C2F5). The rhodium complex [RhH{P(OPh)3}4] in boiling n-heptance loses hydrogen to yield the metallated product [Rh{P(OPh)3}3(pc)].

The nitrosyl complexes [M(NO)(PPh3)3](M = Rh or Ir) react readily with trichloroacetic acid in acetone solution at ambient temperature to afford the dichloro-complexes [MCl2(NO)(PPh3)2] in excellent yield. The rhodium-based reaction performed at ca. 0 °C and quickly worked-up affords the carboxylate complex [Rh(O2CCCl3)2(NO)(PPh3)2] which is stable in pure acetone, but rapidly converts to the dichloride [RhCl2(NO)(PPh3)2] when free trichloroacetic acid and triphenylphosphine are introduced to the solution. The complexes [MCl(CO)(PPh3)2], [MH(CO)(PPh3)3], mer-[IrH3(PPh3)3], and [RhCl(PPh3)3] also react with trichloroacetic acid to form trichloroacetates which undergo similar ligand fragmentation reactions. Reaction pathways involving formation of CCl3–, Cl–, :CCl2, and CO2 fragments are outlined; hydrolysis of dichlorocarbene affords carbonyl ligands. Similar reactions have been observed with tribromoacetic acid.

A multinuclear (1H, l3C, 31P, and 103Rh), variable-temperature, n.m.r. study on some [Rh2(O2CR)4]–P(OR′)3 systems (R = Me, Et, Pr, or Ph; R′= Me, Et, or Ph) is reported. The ambient-temperature (298 K) spectra, which generally display broad unresolved signals with no discernible internuclear couplings, are consistent with the establishment in solution of dynamic equilibria of the form [{(R′O)3P}Rh(O2CR)4Rh{P(OR′)3}]⇌[{(R′O)3P}Rh(O2CR)4Rh(solv)]+ P(OR′)3(solv = solvent). Low-temperature (ca. 213 K) spectra of the same solutions show fully resolved resonances indicative of a frozen equilibrium mixture containing mono and bis adducts together with free phosphorus-donor ligands. The large 31P chemical shift difference (ca. 50–60 p.p.m.) between the mono and bis adducts points to the operation of a strong trans influence across the binuclear metal centre. This has been confirmed by a study of ca. 30 mixed adducts [{(MeO)3P}Rh(O2CMe)4RhL] in which 31P chemical shifts and 2J(RhP) coupling constants have been employed to establish a trans-influence series for the ligands L.

Many hydrido- and low oxidation state triphenylphosphine complexes of ruthenium, osmium, rhodium, and iridium are shown to yield carboxylato-derivatives on reaction with carboxylic acids R·CO2H (R = alkyl or aryl) in organic solvents. These reactions provide convenient syntheses for an extensive range of new and previously reported series of carboxylato-complexes including RuH(OCOR)(PPh3)3, RuCl(OCOR)(CO)(PPh3)2, RuH(OCOR)(CO)(PPh3)2 Ru(OCOR)2(CO)(PPh3)2, Ru(OCOR)2(CO)2(PPh3)2, OsH(OCOR)(PPh3)3, Rh(OCOR)(PPh3)3, Rh(OCOR)(CO)(PPh3)2[Rh(Ph2P·CH2·CH2·PPh2)2][OCOR], Rh(OCOR)2(NO)(PPh3)2, IrH2(OCOR)(PPh3)3, and Ir(OCOR)3(PPh3)2. A single-step synthesis of the complexes RuH(OCOR)(PPh3)3 from hydrated ruthenium trichloride is also described. The carboxylato-derivatives are characterised by i.r. and 1H n.m.r. spectroscopy.

An extensive series of triaryl phosphite derivatives of palladium(II) and platinum(II) dihalides, MX2[P(OAr)3]2(M = Pd or Pt; X = Cl, Br, or I; Ar = phenyl, p-chlorophenyl, o-, m-, or p-tolyl), have been isolated as air-stable crystalline solids by reacting triaryl phosphites, P(OAr)3 and, where appropriate, lithium halides, LiX, with the salts Na2MCl4 in ethanol or the neutral complexes MX2(cyclo-octa-1,5-diene) in benzene solution. The new complexes have been characterised and their stereochemistry investigated by i.r. and n.m.r. spectroscopy. Palladium derivatives containing bulky tri-o-tolyl phosphite or iodide ligands were obtained as trans-isomers or cis–trans mixtures, the remaining complexes occurred predominantly as the cis-isomers. An extensive compilation of 31P n.m.r. data is given.

Convenient routes to some arylazo and aryldi-imine derivatives of ruthenium, osmium, and rhodium are described; the reported complexes ‘RhCl2(N2Ar)(PPh3)2,½CH2Cl2’ are reformulated as aryldi-imine derivatives RhCl3(NHNAr)(PPh3)2.

Arylazo derivatives RuX3(N2Ar)(PPh3)2, OsBr3(N2Ar)(PPh3)2, and RhX2(N2Ar)(PPh3)2 have been prepared by reacting diazonium tetrafluoroborates with the preformed metal phosphine complexes RuX2(PPh3)3, OsBr2(PPh3)3, and RhX(PPh3)3 respectively then adding the appropriate lithium halide to the reaction mixture. The ruthenium and rhodium arylazo complexes are also conveniently prepared by a single step procedure involving addition of the appropriate metal trihalide and 1,3-diaryltriazene to an ethanolic solution of a triarylphosphine. These latter reactions are thought to involve diazonium cations generated in situ by acidolysis of 1,3-diaryltriazene. Products obtained on reacting RhHCl2(PPh3)3 with diazonium tetrafluoroborates and lithium chloride, and previously formulated by other workers as solvated arylazo derivatives RhCl2(N2Ar)(PPh3)2(sol)x(x=½–1; sol = CH2Cl2 or CHCl3), are reformulated as aryldi-imine derivatives RhCl3(NHNAr)(PPh3)2. Similar reactions of the hydrides MHCl(CO)(PPh3)3 and MH2(CO)(PPh3)3(M = Ru or Os) with diazonium salts afford new aryldi-imine derivatives of ruthenium and osmium. The interconversion of arylazo and aryldi-imine complexes is reported and the carbonylation and hydrogenation of some of these products are described. The structure of the aryldi-imine ligands is confirmed by 1H n.m.r. spectroscopy using 15N labelled ligands. Structural and spectroscopic analogies between isoelectronic arylazo and nitrosyl complexes are discussed.

Previously reported, convenient, single-stage syntheses for important hydride, carbonyl, and nitrosyl containing triphenylphosphine complexes of the platinum group metals have been further improved by use of ethanolic potassium hydroxide or triethylamine in place of sodium borohydride as basic reducing agent. The technique has also been extended to include convenient new syntheses for the ruthenium and osmium triphenylphosphine derivatives. cis-RuCl2(CO)2(PPh3)2, OsHCl(CO)(PPh3)3, OsH2(CO)(PPh3)3, and OsH2(CO)2(PPh3)2. The stereochemistry of these last-named complexes is discussed. Attempts to extend this mode of synthesis to include derivatives of other triarylphosphines are described. New complexes synthesised include Rh(NO)L3[L = P(p-C6H4Cl)3 and P(p-C6H4Me)3] and Ru(CO)3L2[L = P(p-C6H4Me)3 and P(p-C6H4OMe)3].

Triaryl phosphite complexes of palladium(II) and platinum(II), MX2[P(OAr)3]2(M = Pd or Pt; X = Cl, Br, or I; Ar = phenyl, p-chlorophenyl, o-, m-, or p-tolyl), react in boiling decalin, with elimination of a molecule of hydrogen halide. HX, to afford ortho-metallated triaryl phosphite derivatives. The tendency to undergo metallation is dependent upon the anionic ligands present and increases I < Br < Cl. The structures and stereochemistry of these products have been determined by i.r. and n.m.r. spectroscopy. Treatment of the ortho-metallated complexes with hydrogen halide in dichloromethane leads to rapid reversal of the ortho-palladation reactions and slow reversal of the ortho-platination reactions. Mechanistic aspects of the ortho-metallation processes are discussed.