Synthesis of the homoleptic rhodium(III) complex [Rh(C6Cl5)3]. Molecular structures of [Rh(C6Cl5)3] and [Rh(C6Cl4–C6Cl4)(C6Cl5)(SC4H8)2]

Abstract

The arylation of [RhCl₃(SC₄H₈)₃] (SC₄H₈ = tetrahydrothiophene, tht) with the Grignard reagent MgCl(C₆Cl₅), under different reaction conditions, afforded the neutral rhodium(III) complexes [Rh(C₆Cl₅)₃] 1 and [Rh(C₆Cl₄–C₆Cl₄)(C₆Cl₅)(tht)₂] 2 as well as the paramagnetic rhodium(II) compound [Rh(C₆Cl₅)₂(tht)₂] 3. The homoleptic complex 1 can also be obtained by treatment of [P(CH₂Ph)Ph₃][RhCl(C₆Cl₅)₃] with AgClO₄. The complexes are stable to the air and moisture in the solid state and moderately stable in deoxygenated solutions. The crystal structures of compounds 1 and 2 have been determined. They display distorted octahedral environments. All C₆Cl₅ groups in 1 or one C₆Cl₅ group in 2 act as chelating ligands being bonded through the ipso-C atom and one of the ortho-Cl atoms. Complex 2 additionally incorporates two tetrahydrothiophene ligands and a perchloro-2,2′-biphenylene ligand, formed by coupling of two pentachlorophenyl groups.