Structural studies of organoboron compounds. XIII. Preparation and crystal and molecular structure of bis[(salicylaldoximato(2−))phenylboron]

Abstract

The reaction of (C6H5)2BOH with salicylaldoxime yielded [(C7H5NO2)BC6H5]2 via a boron–carbon bond cleavage reaction. Crystals of bis[(salicylaldoximato(2−))phenylboron] are triclinic, a = 9.219(1), b = 11.240(1), c = 12.086(1) Å, α = 100.682(7), β = 112.224(6), γ = 92.189(7)°, Z = 2, space group [Formula: see text]. The structure was solved by direct methods and was refined by full-matrix least-squares procedures to R = 0.036 and Rw = 0.049 for 3433 reflections with I ≥ 3σ(I). The molecule, which has approximate C2 symmetry, contains a system of five fused six-membered rings including the first crystallographically characterized B2N2O2 ring. The compound is stabilized both by intramolecular N → B coordination and by resonance delocalization and contains boron atoms in a distorted tetrahedral environment. Bond lengths (corrected for libration) are: O—B, 1.469(2)–1.488(2), N—B, 1.602(2) and 1.575(2), C—B, 1.598(2) and 1.599(2) Å.