Amidinatogermylene Complexes of Copper, Silver, and Gold

The synthesis of the first amidinatogermylene derivatives of the three coinage metals, including the first silver halide complex containing a germylene ligand of any type, has been achieved by reacting metal chloride precursors with the very bulky amidinatogermylene Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu (^<i>t</i>Bu₂bzam = <i>N</i>,<i>N</i>′-di­(<i>tert</i>-butyl)­benzamidinate). The reactions of Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu with an equimolar amount of MCl (M = Cu, Ag) led to the tetrameric complexes [M₄(μ₃-Cl)₄{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}₄] (M = Cu (<b>1</b>) and Ag (<b>2</b>)), which contain a pseudocubane-type M₄(μ₃-Cl)₄ core. A similar reaction with [AuCl­(tht)] (tht = tetrahydrothiophene) afforded the linear mononuclear derivative [AuCl­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}] (<b>3</b>). The ionic digermylene derivatives [M­{Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu}₂]­[BF₄] (M = Cu (<b>4</b>) and Ag (<b>5</b>)) were satisfactorily prepared from the respective reactions of [Cu­(MeCN)₄]­[BF₄] and Ag­[BF₄] with two equivalents of Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu. The Ge-bound <i>tert</i>-butyl group of Ge­(^<i>t</i>Bu₂bzam)^<i>t</i>Bu plays an important role in stabilizing compounds <b>1</b>–<b>5</b> against hydrolysis, since, under similar reaction conditions, no pure complexes could be isolated from reactions of the same metal precursors with the chlorogermylene Ge­(^<i>t</i>Bu₂bzam)­Cl