Synthesis and molecular structures of dimeric boron compounds

A series of eleven new dimeric boron chelates: [B(SAE)(m-NH2-C6H4)](2) (3a), [B(SAE)(p-CF3-C6H4)](2) (3b), [B(SAE)(p-CHO-C6H4)](2) (3c), [B(SAE)(p-Br-C6H4)](2) (3d),[B(SAE)(p-EtO-C6H4)](2) (3e), [B(SAE)(m-CH3CO-C6H4)](2) (3f), [B(SAE)(p-CH3CO-C6H4)](2) (3g), [B(SAE)(o-F, p-F-C6H3)](2) (3h), [B(SAE)(m-F, p-F-C6H3)](2) (3i), [B(SAE)(m-F, m-F-C6H3](2) (3j) and [B(SAE)(o-F, o-F-C6H3)](2) (3k), prepared by condensation of 2-salicylideneamino hydroxyethane (H(2)SAE) with arylboronic acids such as amino-, trifluoromethyl-, bromo-, formyl-, acetyl-, ethoxy- and difluoro-boronic acid allowed a study of the influence of different substituents in the B-phenyl moiety on coordination of the boron atom. In all cases, dimeric derivatives were formed and the molecular structures for [B(SAE)(p-CH3O-C6H4](2) (2e), 3b, 34 and 3h were established by X-ray diffraction analysis where the values of the intramolecular (N-B) bond lengths confirmed a donor-acceptor character. (C) 2000 Elsevier Science S.A. All rights reserved.