Redetermination of diaqua-tetra-kis-(dimethyl-formamide-κO)magnesium dichloride.

The crystal structure of the title compound, [Mg(C(3)H(7)NO)(4)(H(2)O)(2)]Cl(2), in which the Mg ion lies on a crystallographic inversion centre, confirms that of the previous room-temperature study [Pavanello et al. (1995 ▶). Main Group Met. Chem.18, 9-19]. This redetermination at 113 K has improved geometry precision by almost an order of magnitude [e.g. Mg-O(w) (w = water) distances = 2.094 (4) and 2.0899 (7) Å in the old and new structures, respectively] and allowed the water H atoms to be located and their positions refined. In the crystal, O-H⋯Cl hydrogen bonds between the two aqua ligands of the complex mol-ecule and neighboring chloride counter-anions generate supra-molecular chains propagating along [010]. The dicationic [Mg(DMF)(4)(H(2)O)(2)] unit (DMF is dimethyl-formamide) adopts a slightly distorted octa-hedral geometry in which the Mg atom is coordinated by four DMF O atoms in a pseudo-tetra-gonal arrangement and two trans aqua ligands.