Stephen D. Robinson, Arvind Sahajpal and Derek A. Tocher
Thiobenzamide reacted with the complexes [MCl2(PPh3)3], [MH(X)(CO)(PPh3)3] (M = Ru or Os, X = H or Cl) and mer-[IrH3(PPh3)3] in boiling toluene to afford the products [M{S(NH)CPh}2(PPh3)2], [MX{S(NH)CPh}(CO)(PPh3)2] and [IrH2{S(NH)CPh}(PPh3)2] respectively. The crystal structure of [Os{S(NH)CPh}2(PPh3)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 [MCl2(PPh3)3] and [MH(X)(CO)(PPh3)3] under similar conditions to yield [M{S(O)CPh}2(PPh3)2] and [M{S(O)CPh}2(CO)(PPh3)2] respectively. The reactions of thiobenzoic acid with mer-[IrH3(PPh3)3] under conditions of increasing severity give [IrH2{S(O)CPh}(PPh3)3], [IrH{S(O)CPh}2(PPh3)2] and [Ir{S(O)CPh}3(PPh3)2] the last two of which on carbonylation afford [IrH{S(O)CPh}2(CO)(PPh3)2] and [Ir{S(O)CPh}3(CO)(PPh3)2] respectively. The crystal structure of [IrH{S(O)CPh}2(PPh3)2] has established the presence of trans phosphorus and trans sulfur donor atom pairs, with the η1- and η2-thiobenzoate ligands sharing a meridional set of three co-ordination sites. However, the NMR spectra of this complex show two high-field 1H triplets and two 31P-{1H} singlets. Possible explanations for this anomalous NMR behaviour, which is also found for the corresponding thioacetate, are advanced.