Rhodium(I) and iridium(I) carbonyl complexes with sulphur-donor ligands; X-ray crystal structure of [Rh(CO)2(ButSCHCHSBut)]ClO4

Abstract

The reactivity towards carbon monoxide of cationic complexes of Rh^I and Ir^I containing cyclo-octa-1,5-diene (cod) and sulphur-donor ligands has been studied. Mononuclear five-co-ordinated [Ir(CO)₂(cod)L]ClO₄(L = tetrahydrothiophene, trimethylene sulphide, SMe₂, or SEt₂), binuclear four-co-ordinated [(OC)₂Ir{µ-(L–L)}₂Ir(CO)₂][ClO₄]₂[L–L = Bu^tS(CH₂)₂SBu^t or 1,4-dithiacyclohexane (dtch)], and binuclear five-co-ordinated [(cod)(OC)Ir{µ-(L–L)}₂Ir(CO)(cod)][ClO₄]₂[L–L = Bu^tS(CH₂)₂SBu^t, dtch, or MeSSMe] have been prepared. Rhodium(I) cationic carbonyl complexes of formulation [Rh(CO)₂(L–L)]_n[ClO₄]_n[L–L = dtch or MeS(CH₂)₃SMe] have been obtained from [(OC)₂Rh(µ-Cl)₂Rh(CO)₂]. When the ligand was Bu^tS(CH₂)₂SBu^t the structure of the carbonyl complex obtained was determined by single-crystal X-ray diffraction. Surprisingly, the saturated ligand is found to be converted into Bu^tSCHCHSBu^t giving the complex [Rh(CO)₂(Bu^tSCHCHSBu^t)]ClO₄. The crystals are orthorhombic, space group Ccm2₁. The rhodium is four-co-ordinated to two CO groups and two S atoms in a square-planar fashion. The five-membered chelate ring is planar.