Synthesis and Structure of the Novel 11-Vertex Rhenacarborane Dianion [1,1,1-(CO)₃-2-Ph-<i>c</i><i>loso</i>-1,2-ReCB₉H₉]²^-and Its Reactivity toward Cationic Transition Metal Fragments

Abstract

Treatment of [NEt4][6-Ph-nido-6-CB9H11] in tetrahydrofuran (THF) with BunLi (2 equiv) followed by [ReBr(THF)2(CO)3] gives the title rhenacarborane dianion isolated, by addition of [N(PPh3)2]Cl, as a mixed salt [N(PPh3)2][NEt4][1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H9], whose structure was confirmed by X-ray diffraction. The closo 11-vertex dianion reacts readily with several cationic transition metal−ligand fragments, affording products with novel structures in which the electrophilic metal groups are attached exo-polyhedrally to the {closo-1,2-ReCB9} cage system by rhenium−metal bonds supported by three-center two-electron B−H⇀M linkages. Species prepared include [1,3-{M(dppe)}-3-μ-H-1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H8] (M = Ni, Pd, or Pt; dppe = Ph2PCH2CH2PPh2), [N(PPh3)2][1,3,6-{M(CO)3}-3,6-(μ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H7] (M = Mn or Re), and [1,6-{M(PPh3)}-1,7-{M(PPh3)}-6,7-(μ-H)2-1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H7] (M = Cu or Au). Of these, the structures of the platinum−rhenium and dicopper−rhenium species were confirmed by X-ray diffraction.