Synthesis and Structure of the Novel 11-Vertex Rhenacarborane Dianion [1,1,1-(CO)3-2-Ph-closo-1,2-ReCB9H9]2-and Its Reactivity toward Cationic Transition Metal Fragments

Treatment of [NEt 4 ][6-Ph- nido -6-CB 9 H 11 ] in tetrahydrofuran (THF) with Bu n Li (2 equiv) followed by [ReBr(THF) 2 (CO) 3 ] gives the title rhenacarborane dianion isolated, by addition of [N(PPh 3 ) 2 ]Cl, as a mixed salt [N(PPh 3 ) 2 ][NEt 4 ][1,1,1-(CO) 3 -2-Ph- closo -1,2-ReCB 9 H 9 ], 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-ReCB 9 } 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-ReCB 9 H 8 ] (M = Ni, Pd, or Pt; dppe = Ph 2 PCH 2 CH 2 PPh 2 ), [N(PPh 3 ) 2 ][1,3,6-{M(CO) 3 }-3,6-( μ -H) 2 -1,1,1-(CO) 3 -2-Ph- closo -1,2-ReCB 9 H 7 ] (M = Mn or Re), and [1,6-{M(PPh 3 )}-1,7-{M(PPh 3 )}-6,7-( μ -H) 2 -1,1,1-(CO) 3 -2-Ph- closo -1,2-ReCB 9 H 7 ] (M = Cu or Au). Of these, the structures of the platinum−rhenium and dicopper−rhenium species were confirmed by X-ray diffraction.