Syntheses and Structural Characterizations of Vanada- and Niobatricarbadecaboranyl Monohalide Complexes

The syntheses and structural characterizations of the vanadium and niobium monohalide
tricarbadecaboranyl complexes 1-(η5-C5H5)-1-Br-2-Ph-1,2,3,4-VC3B7H9 (1), [1-(η5-C5H5)-1,1‘-μ-Cl-2-Ph-closo-1,2,3,4-NbC3B7H9]2 (2), [1-(η5-C5H5)-1,1‘-μ-Cl-2-Me-closo-1,2,3,4-NbC3B7H9]2
(3), and commo-Nb-1-Cl-(4-Me-1,2,3,4-NbC3B7H9)2 (4) are described. X-ray crystallographic
studies of 1, 3, and 4 confirmed that they are monohalide complexes in which the V3+ and
Nb3+ ions are sandwiched between cyclopentadienyl and/or tricarbadecaboranyl monoanions.
These compounds are analogues of (η5-C5H5)2VX and (η5-C5H5)2NbX but, unlike their
metallocene counterparts, are air- and water-stable, further illustrating the unique ability
of the tricarbadecaboranyl ligand to stabilize complexes with the metals in lower oxidation
states.