Tris(diphenylthiophosphinoyl)methanide as tripod ligand in rhodium(III), iridium(III) and ruthenium(II) complexes. Crystal structures of [( η5-C 5Me 5)Ir{ η3-(SPPh 2) 3C-S,S′,S″}]BF 4 and [( η6-MeC 6H 4Pr i)Ru{ η3-(SPPh 2) 3C-S,S′,S″}]BPh 4

Abstract

Reaction of the complex [{(η 5-C 5Me 5)RhCl 2} 2], in CH 2Cl 2 solution, with AgBF 4 (1:2 molar ratio) and (SPPh 2) 3CH leads to the cationic compound [(η 5-C 5Me 5)RhCl{η 2-(SPPh 2) 2CH(SPPh 2)-S,S′}]BF 4 ( 1) which is deprotonated by thallium(I) pyrazolate affording [(η 5-C 5Me 5)Rh{η 3-(SPPh 2) 3C−S,S′,S″}]BF 4 ( 2a). The iridium dimer [(η 5-C 5Me 5)IrCl 2} 2] reacts with silver salts and (SPPh 2) 3CH, in CH 2Cl 2 or Me 2CO, under analogous conditions, affording mixtures of [(η 5-C 5Me 5)IrCl{η 2-(SPPh 2) 2)-S,S′}] + and [(η 5-C 5Me 5)Ir{η 3-(SPPh 2) 3C-S,S′,S″}]A [A=BF 4 − ( 3a), PF 6 − ( 3b). Addition of Et 3N to the mixture gives pure complexes 3. The ruthenium complexes [{η 6j6-arene)RuCl 2} 2] (arene = C 6Me 6, p-MeC 6H 4Pr i) react with (SPPh 2) 3CH, in the presence of AgA (A = PF 6 − or BF 4 −) or Na BPh 4, in CH 2Cl 2 or Me 2CO, yielding only the deprotonated complexes [(η 6-arene)Ru{η 3-(SPPH 2) 3C−S,S′,S″}]A [arene = C 6Me 6, A = BF 4; arene = p-MeC 6H 4Pr i, A - BPh 4 ( 4a), PF 6 ( 4b)]. The crystal structures of 3a and 4a were established by X-ray crystallography. Compound 3a crystallizes in the orthorhombic space group Pna2 1, 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 P2 1/ n, with a = 20.810(4), b = 12.555(3), c = 23.008(4) Å, β = 95.82(2)° and Z = 4. Both cationic complexes exhibit analogous pseudo-octahedml molecular structures with the anionic (SPPh 2) 3C − ligand bonded via the three sulphur atoms in a tripodal, tridentate fashion. Each metal centre completes its coordination environment with a η 5-C 5Me 5 ( 3a) or a η 6-MeC 6H 4Pr i 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 IKD in acetonitrile solutions. The Ru(II) complex undergoes a quasi-reversible reduction to Ru(I) and a reversible oxidation to Ru(III).