Synthesis, Reactivity, and Structural Transformation of Mono- and Binuclear Carboranylamidinate-Based 3d Metal Complexes and Metallacarborane Derivatives

A series of carboranylamidinate-based 3d metal complexes
are reported.
Treatments of 3d metal dichlorides (CoCl2, NiCl2(DME), CuCl2) with the lithium salts of carboranylamidines
(CabNH) generate the mononuclear C,N-coordinated
complexes [(RNC­(closo-1,2-C2B10H10)­(NHR)]2M (1–6; M  Co, Ni, Cu; R = iPr, Cy) in
moderate yields, respectively. These complexes have similar structures
in the solid state, in which the metal atom is coordinated to two
nitrogen atoms and bonded to two cage carbon atoms in a distorted-tetrahedral
geometry. As a noninnocent ligand, CabNH can be modified to produce carboranylamidinate thiol (CabNSH) and nido derivatives DcabNH (9, 10), respectively. Reaction
of cupric acetate with 1 equiv of CabNSH gave the binuclear complexes {[RNC­(closo-1,2-C2B10H10)­(NHR)]­SCu}2 (R = iPr (7), Cy (8))
in 66 and 63% yields, respectively. The structure of 7 shows the formation of a Cu–Cu bond, and the geometry of
the Cu2S2 core is planar. The zwitterionic nickel
dicarbollide complexes (DcabN)­Ni­(PPh3)Cl (11, 12) were prepared by reactions
of the lithium salts of DcabNH (9, 10) with NiCl2(PPh3)2 in THF. All complexes were characterized by elemental analysis
and IR and NMR spectroscopy. The structures of 1, 3–5, 7, and 9–11 were
further confirmed by single-crystal X-ray diffraction.