Supraicosahedral and icosahedral nickelacarbaboranes bearing exopolyhedral metal fragments

Abstract

Treatment of the isomeric 12-vertex nickelacarbaborane salts [NEt₄][3-(η³-C₃H₅)-closo-3,1,2-NiC₂B₉H₁₁] and [NEt₄][2-(η³-C₃H₅)-closo-2,1,7-NiC₂B₉H₁₁] with [CuCl(PPh₃)]₄ and Tl[PF₆] affords the zwitterionic bimetallic species [3-(η³-C₃H₅)-3,4,8-{Cu(PPh₃)}-4,8-(μ-H)₂-closo-3,1,2-NiC₂B₉H₉] and [2-(η³-C₃H₅)-2,6,11-{Cu(PPh₃)}-6,11-(μ-H)₂-closo-2,1,7-NiC₂B₉H₉], respectively. Similarly, the 13-vertex nickelacarbaborane [NEt₄][4-(η³-C₃H₅)-closo-4,1,6-NiC₂B₁₀H₁₂] reacts with sources of mono-cationic metal fragments to form [4-(η³-C₃H₅)-7,8,13-{Cu(PPh₃)}-7,8,13-(μ-H)₃-4,1,6-closo-NiC₂B₁₀H₉], [4-(η³-C₃H₅)-3,8-{Rh(PPh₃)₂}-3,8-(μ-H)₂-4,1,6-closo-NiC₂B₁₀H₁₀] and [4-(η³-C₃H₅)-3,7,8-{RuCl(PPh₃)₂}-3,7,8-(μ-H)₃-4,1,6-closo-NiC₂B₁₀H₉]. The molecular structures of these five new bimetallic compounds were determined by X-ray diffraction studies, confirming that exopolyhedral Cu, Rh and Ru fragments are attached to the cluster via B–H⇀M agostic-type interactions and, in the case of the {NiC₂B₉} species, by a metal–metal bond.