All -cis-1,2,3,4,5,6-cyclohexanehexacarboxylate two-dimensional gadolinium(III) complexes: Synthesis, X-ray crystal structure and magnetic properties

Abstract

The first gadolinium(III) complexes with the trideprotonated form of the 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H 3clhex 3−) of formulae [Gd(H 3clhex)(H 2O) 4] n ·3nH 2O ( 1) and [Gd(H 3clhex)(H 2O) 4] n ·6nH 2O ( 2) have been prepared through the gel technique and their structures determined by single crystal X-ray diffraction. The structure of 1 is made up of 6 3 honey-comb layers which are generated by [Gd(H 2O) 4] 3+ cations and H 3clhex 3− anions acting as three-fold nodes and three-fold connectors, respectively. The structure of 2 consists of a [4 4,6 2] two-dimensional network extended in the ac plane where the H 3clhex −3 groups act as four-fold connectors and the [Gd(H 2O) 4] 3+ units as four-fold nodes. Compound 1 crystallises in a non-centrosymmetric space group P2 1. Its absolute structure could be determined reliably, indicating the spontaneous resolution of a homochiral crystal and the freezing of one of the conformations of the all- cis H 3clhex −3 ligand. Compound 2 crystallises in the P2 1/ n space group, the presence of an inversion centre making both conformations to occur. 1 and 2 are different solvates of the same system, the latter one synthesised under a higher pH value of the gel than the former. The investigation of the magnetic properties of 1 and 2 in the temperature range 1.9–300 K reveals a Curie law behaviour for the two compounds.