Crystal structure of gadolinium(III) acetate tetrahydrate. Stereo-chemistry of the nine-co-ordinate [M(bidentate ligand)3(unidentate ligand)3]x± system

Abstract

The crystal structure of the title compound has been determined by single-crystal X-ray diffraction at 295(1) K and refined by least squares to a residual of 0.034 for 2 874 ‘observed’ reflections. Crystals are triclinic, space group P1, with a= 10.790(2), b= 9.395(3), c= 8.941 (3)Å, α= 60.98(2), β= 88.50(2), γ= 62.31 (2)°, and Z= 2. The compound is isostructural with its erbium analogue and comprises a dimeric species with the two rare-earth metal atoms bridged by acetate oxygen atoms; the co-ordination number of each rare-earth metal atom is nine, through the three bidentate acetate groups, two water molecules, and a bridging oxygen from one of the adjoining acetates. Bond lengths (Gd–O) range from 2.368(6) to 2.571(4)Å. The co-ordination stereochemistry for the [M(bidentate)₃(unidentate)₃]^x± is examined in terms of a repulsion model.