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(tBu2bzam)tBu (tBu2bzam = N,N′-di­(tert-butyl)­benzamidinate).
The reactions of Ge­(tBu2bzam)tBu with an equimolar amount of MCl (M = Cu,
Ag) led to the tetrameric complexes [M4(μ3-Cl)4{Ge­(tBu2bzam)tBu}4] (M = Cu (1)
and Ag (2)), 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(tBu2bzam)tBu}] (3). The ionic digermylene
derivatives [M­{Ge­(tBu2bzam)tBu}2]­[BF4] (M
= Cu (4) and Ag (5)) were satisfactorily
prepared from the respective reactions of [Cu­(MeCN)4]­[BF4] and Ag­[BF4] with two equivalents of Ge­(tBu2bzam)tBu.
The Ge-bound tert-butyl group of Ge­(tBu2bzam)tBu
plays an important role in stabilizing compounds 1–5 against hydrolysis, since, under similar reaction conditions,
no pure complexes could be isolated from reactions of the same metal
precursors with the chlorogermylene Ge­(tBu2bzam)­Cl.