Abstract

Reaction of the complex [{(?5-C5Me5)RhCl2}2], in CH2Cl2 solution, with AgBF4 (1:2 molar ratio) and (SPPh2)3CH leads to the cationic compound [(?5-C5Me5)RhCl{?2-(SPPh2)2CH(SPPh2)-S,S?}]BF4 (1) which is deprotonated by thallium(I) pyrazolate affording [(?5-C5Me5)Rh{?3-(SPPh2)3C-S,S?,S?}]BF4 (2a). The iridium dimer [{(?5-C5Me5)IrCl2}2] reacts with silver salts and (SPPh2)3CH, in CH2Cl2 or Me2CO, under analogous conditions, affording mixtures of [(?5-C5Me5)IrCl{?2-(SPPh2)2CH(SPPh2)-S,S?}]+ and [(?5-C5Me5)Ir{?3-(SPPh2)3C-S,S?,S?}]A [A = BF- 4 (3a), PF- 6 (3b)]. Addition of Et3N to the mixture gives pure complexes 3. The ruthenium complexes [{(?6-arene)RuCl2}2] (arene = C6Me6, p-MeC6H4Pri) react with (SPPh2)3CH, in the presence of AgA (A = PF- 6 or BF- 4) or Na BPh4, in CH2Cl2 or Me2CO, yielding only the deprotonated complexes [(?6-arene)Ru{?3-(SPPh2)3C-S,S'?,S?}]A [arene = C6Me6, A = BF4; arene = p-MeC6H4Pri, A = BPh4 (4a), PF6 (4b)]. The crystal structures of 3a and 4a were established by X-ray crystallography. Compound 3a crystallizes in the orthorhombic space group Pna21, with lattice parameters a = 41.477(6), b = 10.6778(11), c = 20.162(3) Å and Z = 8. Complex 4a crystallizes in a monoclinic lattice, space group P21/n, with a = 20.810(4), b = 12.555(3), c = 23.008(4) Å, ? = 95.82(2)° and Z = 4. Both cationic complexes exhibit analogous pseudo-octahedral molecular structures with the anionic (SPPh2)3C- ligand bonded via the three sulphur atoms in a tripodal, tridentate fashion. Each metal centre completes its coordination environment with a ?5-C5Me5 (3a) or a ?6-MeC6H4Pri group (4a). A quite interesting result concerns the non-planarity of the methanide carbon which display P-C-P angles in the range 112.6-114.4(5)° in 3a and 111.9-113.6(4)° in 4a. The redox chemistry of the complexes was investigated by cyclic voltammetry. The Rh(III) complexes are quasi-reversibly reduced to Rh(I) and the Ir(III) complex is irreversibly reduced to Ir(I) in acetonitrile solutions. The Ru(II) complex undergoes a quasi-reversible reduction to Ru(I) and a reversible oxidation to Ru(III). © 1997 Elsevier Science S.A.