Novel bonding mode and reaction of a phosphonium-betaine ligand S2C(H)(PPh3). Synthesis of the [Rh(XB10H10){S2C(H)(PPh3)}]2 dimers (X = Se, Te) and X-ray diffraction study of the te-compound

Abstract

The novel dimers [Rh(XB₁₀H₁₀){S₂C(H)(PPh₃)}]₂(XSe,Te), obtained from the reaction of closo-[2,2-(PPh₃)₂-2-(H)-1,2-XRhB ₁₀H₁₀] and CS₂, exist in equilibrium (dichloromethane solution) with monomeric [2-(PPh₃)-2-(η²-S₂CH)-1,2-XRhB ₁₀H₁₀] species, and exhibit a unique cis-bis(phosphonium-betaine) intercluster linkage with each ligand having one S atom bridging both Rh atoms and the other S atom singly co-ordinating to a Rh atom.