First example of a borate-bridged dimeric aluminum Schiff-base complex containing five-coordinate metal centers

Abstract

The formation of a borate-bridged dimeric aluminum Schiff-base compound [salen(1Bu)A-1]2O2BOMe [salen = N,N'-ethylenebis(salicylidenimine) (1) has been reported. Complex 1 crystallizes in a triclinic Pī space group with a=14.57, b=15.15, c=15.84, A and α=96.92, β=90.82, γ=105.53°. The crystal structure shows the presence of a metaborate (MeOBO2 2-) bridge between two five-coordinate aluminum atoms with a bridging OBO angle of 123.25°. The compound has been characterized by 1H, 13C, 11B, 27Al NMR, IR and mass spectroscopies and melting point measurements. 1H NMR shows two complex multiplets for the tBu groups and two different environments for the imine protons. 11B NMR shows a peak at 18 ppm characteristic of three-coordinate boron and 27Al NMR shows a peak at 29 ppm characteristic of five-coordinate aluminum.