Arvind Sahajpal

N,N′-Diphenylthioureido complexes of ruthenium, osmium and iridium ☆

Abstract 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.

N,N′,N″-Triphenylguanidinate(−1) complexes of ruthenium, osmium and iridium: synthesis and X-ray crystal structures

Abstract 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).

Complexes of the platinum metals. Part 39. Salicylaldehydato(2–) derivatives of ruthenium, osmium, and iridium. X-Ray crystal structures of [Ru(OC6H4CO)(HOC6H4CH2OH)(CO)(PPh3)2]·CH2Cl2 and [Ru(OC6H4CO)(MeOH)(CO)(PPh3)2]·MeOH

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.

Amide metallation reactions: synthesis and X-ray crystal structures of [Ru(NHCOCF3)2(H2O)(CO)(PPh3)2], [Ph3P)(OC)Ru(µ-NHCOC6H4-o)(µ-NHCOPh)(µ-H)Ru(CO)(PPh3)2] and [Ru2(µ-Cl)(µ-H)(µ-NHCOCF3)2(PPh3)4]

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.

Reactions of di-isopropylcarbodi-imide with some ruthenium and osmium hydrides, leading to ready dehydrogenation of an isopropyl group; crystal and molecular structure of carbonylchloro(N-isopropenyl-N′-isopropylformamidinato)bis(triphenylphosphine)ruthenium(II)

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.

Complexes of the platinum metals. Part 42. Binuclear N,O-succinimido-bridged ruthenium(II) derivatives: crystal structure of [Ru2(µ-Cl)(µ-H)(µ-C4H4NO2)2(PPh3)4]·2CH2Cl2·0.5H2O

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.

N,N′-Diphenylguanidinato complexes of ruthenium,osmium and iridium*

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.

Thiobenzamidato and thiobenzoato complexes of ruthenium, osmium and iridium

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.

Perfluoroalkyl- and perfluoroaryl-amidato derivatives of ruthenium, osmium and iridium

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.

Complexes of the platinum metals. Part 46. 1,1,1,5,5,5-Hexafluoro-3-azapentane-2,4-diiminato derivatives of ruthenium, osmium and iridium. Crystal structure of [Ru{NHC(CF3)NC(CF3)NH}H(CO)(PPh3)2]

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.