Synthesis and molecular structures of dimeric boron compounds

Abstract A series of eleven new dimeric boron chelates: [B(SAE)( m -NH 2 C 6 H 4 )] 2 ( 3a ), [B(SAE)( p -CF 3 C 6 H 4 )] 2 ( 3b ), [B(SAE)( p -CHOC 6 H 4 )] 2 ( 3c ), [B(SAE)( p -BrC 6 H 4 )] 2 ( 3d ), [B(SAE)( p -EtOC 6 H 4 )] 2 ( 3e ), [B(SAE)( m -CH 3 COC 6 H 4 )] 2 ( 3f ), [B(SAE)( p -CH 3 COC 6 H 4 )] 2 ( 3g ), [B(SAE)( o- F, p -FC 6 H 3 )] 2 ( 3h ), [B(SAE)( m- F, p -FC 6 H 3 )] 2 ( 3i ), [B(SAE)( m- F, m -FC 6 H 3 )] 2 ( 3j ) and [B(SAE)( o- F, o -FC 6 H 3 )] 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 -CH 3 OC 6 H 4 )] 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.