Unprecedented Formation of the First Alkaline‐Earth‐Metal Complex Bearing an Asymmetrical gem‐ Dithiolato Heteroscorpionato Ligand

The reaction of the lithium dithioacetate derivative [Li(bdmpzdta)(THF)] [bdmpzdta = bis(3,5‐dimethylpyrazol‐1‐yl)dithioacetate] with 1 equiv. of C 3 H 5 MgCl proceeds in high yield to give the first alkaline‐earth‐metal complex bearing an asymmetrical gem ‐dithiolato moiety, namely, [Mg(κ 3 ‐NNS‐μ‐S‐bppbte)] 3 ( 1 ) [bppbte = 1,1‐bis(3,5‐dimethyl‐1 H ‐pyrazol‐1‐yl)pent‐4‐ene‐2,2‐bis(thiolate)]. This is achieved through an unprecedented insertion reaction of the allyl group into the C=S bond. In contrast, the reaction with the Grignard reagents MeMgCl or EtMgCl leads to the formation of the six‐coordinate sandwich species [Mg(κ 3 ‐bdmpzdta) 2 ] ( 2 ), as a result of a rapid ligand redistribution. The molecular structures of 1 and 2 in the solid state have been unambiguously established by single‐crystal X‐ray diffraction studies, which reveal a trinuclear entity with a twisted six‐membered core for 1 , in which all magnesium centers are arranged in a distorted trigonal bipyramidal geometry, whereas in 2 the magnesium center has an octahedral coordination environment with two heteroscorpionato ligands, which bind in a κ 3 ‐NNS fashion with a relative trans disposition.