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

The first gadolinium(III) complexes with the trideprotonated form of the 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H3clhex3−) of formulae [Gd(H3clhex)(H2O)4]n·3nH2O (1) and [Gd(H3clhex)(H2O)4]n·6nH2O (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 63 honey-comb layers which are generated by [Gd(H2O)4]3+ cations and H3clhex3− anions acting as three-fold nodes and three-fold connectors, respectively. The structure of 2 consists of a [44,62] two-dimensional network extended in the ac plane where the H3clhex−3 groups act as four-fold connectors and the [Gd(H2O)4]3+ units as four-fold nodes. Compound 1 crystallises in a non-centrosymmetric space group P21. 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 H3clhex−3 ligand. Compound 2 crystallises in the P21/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.

The first two all-cis-1,2,3,4,5,6-cyclohexanehexacarboxylate gadolinium(III) complexes have been prepared through the gel technique, their structures determined by X-ray diffraction on single crystals and their magnetic properties investigated. In both complexes, the 1,2,3,4,5,6-cyclohexanehexacarboxylate is triprotonated and act as a tricarboxylate ligand, leading to two-dimensional [63] and [44,62] networks.Figure optionsDownload as PowerPoint slide