Structure and formation of dichloro(benzylacetophenone)bis(dimethylsulphoxide)iridium(III)

Abstract

Crystals of [Ir(C₁₅H₁₃O)Cl₂(Me₂SO)₂] are triclinic with a= 7·471, b= 11·505, c= 13·609 Å, α= 101·45, β= 107·98, γ= 89·90°, Z= 2, space group P. Least-squares refinement of atomic positional and vibrational parameters has been based on diffraction intensities of 2301 independent reflexions measured on a PAILRED diffractometer; the final unweighted discrepancy index is 0·073. The iridium has a distorted octahedral co-ordination made up of two dimethylsulphoxide molecules co-ordinated through their sulphur atoms [Ir–S 2·229(7) and 2·243(7)Å], two chloride ions [Ir–Cl 2·376(9) and 2·496(9)Å] and a benzylacetophenone ring forming a puckered five-membered chelate ring [Ir–02·09(2)Å and Ir–C 2·16(2)Å]. Those bond lengths are discussed in detail with particular reference to the trans-influence of ligands in octahedral complexes. The geometry of the chelate ring strongly suggests that the complex has been formed by a Markownikoff addition reaction and this is discussed in relation to other catalytic processes.