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

The title compound, di-μ(3)-chlorido-tetra-μ(2)-chlorido-tetra-kis-(diethyl ether-κO)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.