U(2)-PINACOLATO-O,O')-BIS(PINACOLATO-O,O')-DIBORON

The title compound, dioxy)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane, C18H36B2O6, B(2)pin(3), has two trigonal planar B atoms, each chelate d by one pinacolato group, linked by a third pinacolate. The molecule is centrosymmetric, with an exactly anti conformation for the bridging pinacolate, and the two Bpin five-membered rings have a twist conform ation with torsion angle O-C-C-O = -27.39 (13)degrees. The B-O bonds t o the bridging pinacolate [1.353(2)Angstrom] are slightly shorter than the chelate B-O bonds [1.367(2) and 1.373 (2) Angstrom].