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 (H2SAE) 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, 3d and 3h were established by X-ray diffraction analysis where the values of the intramolecular (NB) bond lengths confirmed a donor–acceptor character.