Crystal structure of [ t BuMgCl] 2 [MgCl 2 (Et 2 O) 2 ] 2 .

The title compound, di-μ 3 -chlorido-tetra-μ 2 -chlorido-tetra-kis-(diethyl ether-κ O )bis-(1,1-di-methyl-eth-yl)tetra-magnesium, [Mg 4 (C 4 H 9 ) 2 Cl 6 (C 4 H 10 O) 4 ], features an Mg 4 Cl 6 open-cube cluster. The two four-coordinate Mg 2+ ions show an almost tetra-hedral coordination, whereas the two six-coordinate Mg 2+ ions have their ligands in an octa-hedral environment. The Mg-Cl bond lengths differ depending on the coordination number (2 or 3) of the bridging μ-Cl - ligands. There are few comparable structures deposited in the Cambridge Structural Database.