Synthesis and Characterization of Ge(II), Sn(II), and Pb(II) Monoamides with −NH₂ Ligands

The synthesis and characterization of the first divalent germanium, tin, and lead monoamide derivatives of the parent amide group −NH2 are presented. They have the general formula (ArMNH2)2 (M = Ge, Ar = Ar‘ (C6H3-2,6-Pri2) or Ar* (C6H3-2,6(C6H2-2,4,6-Pri3)); M = Sn, Ar = Ar*; M = Pb, Ar = Ar*). For germanium and tin, they were obtained by reacting the corresponding terphenyl halides of the group 14 elements with liquid ammonia in diethyl ether. The lead amide derivative (Ar*PbNH2)2 was synthesized by reaction of LiNH2 with Ar*PbBr in diethyl ether. The compounds were characterized by IR and multinuclear NMR spectroscopies and by X-ray crystallography in the case of the (Ar‘GeNH2)2 or (Ar*SnNH2)2 derivatives. They possess dimeric structures with two −NH2 groups bridging the germanium and tin centers. For lead, the reaction with ammonia led to isolation of a stable ammine complex of formula Ar*PbBr(NH3) which was characterized by IR and NMR spectroscopies and by X-ray crystallography. It is the first structural characterization of a divalent lead ammine complex.