Preparation and characterization of the seven coordinate cadmium(II) complex [Cd(3,4-H 2dhb) 2(H 2O) 3] · HCl · (3,4-H 3dhb) · 2.5H 2O; the first structural determination of a complex containing the 3,4-dihydroxybenzoato(−1)(3,4-H 2dhb −) ligand

Abstract

The 1:2:1 reaction of CdCl 2·2.5H 2O with 3,4-dihydroxybenzoic acid (3,4-H 3dhb) and KOH in Pr nOHH 2O gave the unique, seven-coordinate cadmium(II) complex [Cd(3,4-H 2dhb) 2(H 2O) 3]·HCl·(3,4-H 3dhb)·2.5H 2O as one of the products. Crystal structure and 13Cd NMR studies showed that 3,4-H 2dhb − behaves as a bidentate chelate with ligated atoms being the carboxylate oxygens, but the seven-coordination is not retained in aqueous solution.