Structural studies of organoboron compounds LXIV. Boron chelate formation with glycolohydroxamic acids, and the crystal and molecular structure of 5-(1-hydroxycyclohexyl)-2,2-diphenyl-1,3-dioxa-4-azonia-2-borata-4-cyclopentane

Abstract

The syntheses of representative diphenyl- and difluoroboron chelates of 2-hydroxycarbohydroxamic acids (glycolohydroxamic acids) are reported. Crystals of 5-(1-hydroxycyclohexyl)-2,2-diphenyl-1,3-dioxa-4-azonia-2-borata-4-cyclopentene, 2a, are triclinic, a = 11.5717(5), b = 11.7262(4), c = 14.3529(5) Å, α = 90.277(6)°, β = 110.497(5)°, γ = 96.814(5)°, Z = 4, space group [Formula: see text] The structure was solved by direct methods and refined by full-matrix least-squares procedures to R = 0.042 and Rw = 0.056 for 5318 reflections with I ≥ 3σ(F2). Compound 2a is the first N-unsubstituted hydroxamatoborate derivative to be structurally characterized by an X-ray crystallographic analysis. The solid state structure of 2a consists of centrosymmetric, hydrogen-bonded tetrameric units that also feature intermolecular [Formula: see text](aromatic) interactions. Bond lengths include: B—O(N) = 1.557(2) and 1.553(2) Å, B—O(N) = 1.558(2) and 1.566(2),Å B—C(phenyl) = 1.592(3)–1.601(3) Å. Key words: hydroxamatoborate, organoboron compound, crystal structure.