Synthesis and structure of tetra-aqua-bis-(dimethyl ether)magnesium(II) dibromide dimethyl ether disolvate

Unlike typical hexa-hydrates, the title compound, [Mg(C₂H₆O)₂(H₂O)₄]Br₂·2C₂H₆O or [Mg(H₂O)₄(DME)₂]Br₂·DME₂ (DME = dimethyl ether, C₂H₆O), is a water-poor magnesium(II) complex. The central magnesium cation (site symmetry 1) is coordinated by four water mol-ecules and two mol-ecules of dimethyl ether and adopts a slightly elongated trans-octa-hedral coordination geometry. The water mol-ecules are linked to outer-sphere bromide anions and additional dimethyl ether mol-ecules via O-H⋯Br and O-H⋯O hydrogen bonds. Due to the volatility of dimethyl ether, the presence of coordinating and non-coordinating mol-ecules of this ether makes this solid state structure presented here particularly inter-esting. To investigate the inter-molecular inter-actions leading to this special coordination, a Hirshfeld surface analysis was performed. It showed that the H⋯H inter-actions (70.4%) make the largest contribution to the crystal packing, followed by H⋯Br inter-actions (19.4%), H⋯O inter-actions (10.1%) and Br⋯O inter-actions (0.1%).