Complexes of the platinum metals. Part 43. N,N′-diphenylamidinato derivatives of ruthenium, osmium and iridium

Abstract

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.