Dimeric rhodium(III), iridium(III) and ruthenium(II) thiosalicylate complexes

Reactions of the chloride-bridged dimers [LMCl(μ-Cl)]2 (M=Rh, Ir; L=Cp*=η5-C5Me5; M=Ru, L=η6-p-cymene) with two mole equivalents of thiosalicylic acid (HSC6H4CO2H, H2tsal) and excess base gives the dimeric rhodium(III), iridium(III) and ruthenium(II) thiosalicylate complexes [LM(tsal)]2. Reaction of the complex [Cp*RhCl2(PPh3)] with one equivalent of H2tsal and triethylamine in dichloromethane gives a mixture of the dimer [Cp*Rh(tsal)]2 and the phosphine complex [Cp*Rh(tsal)(PPh3)]; upon recrystallisation, pure dimer is obtained. A single-crystal X-ray diffraction study on the rhodium and ruthenium dimers reveals the expected thiolate-bridged M2(μ-S)2 unit. Electrospray mass spectrometry (ESMS) is a useful technique in studying the chemistry of the thiosalicylate complexes, all complexes giving strong [M+H]+ ions. With added thiosalicylic acid, cations of the type [(LM)2(Htsal)3]+ were detected in the mass spectra.