NOVEL BORON CHELATE COMPLEXES FROM THE REACTION OF SALICYLALDEHYDES, TERTIARY-AMINES, AND DIPHENYLBORINIC OR PHENYLBORONIC ACID - CRYSTAL AND MOLECULAR-STRUCTURES OF 2 NEW TYPES OF CHELATED ORGANOBORATE SALTS

The one-pot reaction of equimolar amounts of salicylaldehyde, diphenyl borinic acid anhydride, and a tertiary amine in the presence of an alk anol (R'OH) led to the addition of R'OH to the aldehyde group and the formation of an O,O-acetal moiety within the chelate anion with the ch arge balanced by an ammonium cation arising from the tertiary amine. E xchanging the diphenylborinic acid in the three-component reaction sys tem for phenylboronic acid did not give the analogous adduct or chelat e but one additional mole equivalent of phenylboronic acid (anhydride) was incorporated, leading to a polycyclic anion containing pyroborona te and acetal boronate functions with an associated ammonium cation. C rystals of 1-methylpiperidinium ,3-dioxa-2-borata-1,2,3,4-tetrahydrona phthalenate, 6d, are monoclinic, a = 9.522(1), b = 17.703(1), c = 14.9 74(1) Angstrom, beta = 98.275(10)degrees, Z = 4, space group P2(1)/n, and those of 1-methylpiperidinium 6-borata-5,6,7,8,9,10-hexahydrobenzo cyclooctenate, 10e, are monoclinic, a = 7.968(1), b = 19.3707(4), c = 15.9400(5) Angstrom, beta = 100.186(5)degrees, Z = 4, space group P2(1 )/n. The structures were solved by direct methods and refined by full- matrix least-squares procedures to R = 0.050 and 0.033 (R-w = 0.040 an d 0.032) for 2815 and 3529 reflections with I greater than or equal to 3 sigma(F-2), respectively. Compounds 6d and 10e are both representat ive of new classes of organoboron chelates.