Salen-supported dinuclear and trinuclear boron compounds

Six boron compounds have been synthesized through the combination of phenylboronic acid and various Salen (N,N'-ethylenebis(2-hydroxy)benzylidenimine) ligands. They contain seven- and eight-membered heterocycles with a bridging oxygen and have the formula: L[(PhB)(2)(mu-O)] (L = Acmen (1), Salen((t)Bu) (2), Sal(2-OH)pen (3), Salpen((t)Bu) (4), Acpen (5)) and L[B(2)(mu-O)(O(2)BPh)] (L = Acen (6), Salmen (7)). Compounds 6 and 7 are interesting trinuclear boron derivatives with two four-coordinate and one three-coordinate boron atoms. The compounds have been characterized by MP, MS, IR, EA and (1)H- and (11)B-NMR, by (11)B-MAS for 6 and 7 and by X-ray crystallography for 2, 4-7. (C) 2002 Elsevier Science B.V. All rights reserved.