STRUCTURAL STUDIES OF ORGANOBORON COMPOUNDS LXVIII - -(2-HYDROXYARYL)-N-(2-HYDROXYPHENYLMETHYL)NITRONES AS REGIOSELECTIVE BIDENTATE LIGANDSIN BORON CHELATE FORMATION - CRYSTAL AND MOLECULAR-STRUCTURES OF A DIPHENYLBORON COMPLEX AND ITS PARENT LIGAND

The -(2-hydroxyaryl)-N-(2-hydroxyphenylmethyl)nitrones 5 are synthesiz ed by the condensation of variously substituted salicylaldehydes with N-(2-hydroxyphenylmethyl)-hydroxylamine. These nitrones react with dip henylborinic acid anhydride to form seven-membered diphenylboron chela tes 6. Crystals of C-(4-diethylamino-2-hydroxyphenyl)-N- (2-hydroxyphe nylmethyl)nitrone, 5d, are monoclinic, a=6.911(2), b= 10.663(2), c = 2 2.951(1) Angstrom, beta = 97.33(1)degrees, Z= 4, space group P2(1)/n, and those of -8-azonia-6-borata-6,7-dihydro-5H-benzocyclohepten e-etha nol, 6d-EtOH, are monoclinic, a = 9.069(2), b = 29.881(1), c = 11.1883 (6) Angstrom, beta = 109.426(9)degrees, Z = 4, space group P21/n. The structures were solved by direct methods and refined by full-matrix le ast-squares procedures to R = 0.032 and 0.039 (R-w = 0.031 and 0.036) for 2510 and 4162 reflections with l> 3 sigma(I), respectively.