The First Nickelacarborane with closo-nido Structure

The first nickelacarborane with closo-nido structure [10′,11′-(Py)(2)-3,9′-Ni(1,2-C(2)B(9)H(11))(7′,8′-C(2)B(8)H(8))] was isolated from the reaction of nickel(IV) bis(dicarbollide) with pyridine. The molecular structure of this complex was determined by single crystal X-ray diffraction. The nickel atom is a common vertex for the closo-NiC(2)B(9) cluster and the nido-NC(2)B(8) cluster where it is located together with carbon atoms in the open NiC(2)B(2) pentagonal face. It is assumed that its formation proceeds through the nucleophile-induced removal of the B(6)H vertex followed by rearrangement of the forming 11-vertex cluster, which most likely proceeds through a sequence of closing and opening reactions.