A dipyrromethane-based diphosphane-germylene as precursor to tetrahedral copper(i) and T-shaped silver(i) and gold(i) PGeP pincer complexes.

A six-membered ring N-heterocyclic germylene flanked by two CH2PiPr2 groups, Ge(pyrmPiPr2)2CMe2 (1; (HpyrmPiPr2)2CMe2 = 5,5-dimethyl-1,9-bis(di-isopropylphosphanylmethyl)dipyrromethane), has been prepared in high yield. Upon treatment with group 11 metal precursors of the type [MCl(PPh3)]n (M = Cu (n = 4), Ag (n = 4), Au (n = 1)), germylene 1 easily forms a PGeP chloridogermyl ligand that is able to stabilize tetrahedral copper(i) and unusual T-shaped silver(i) and gold(i) PGeP pincer complexes, as has been demonstrated by the isolation of [Cu{κ3P,Ge,P-GeCl(pyrmPiPr2)2CMe2}(PPh3)] (2) and [M{κ3P,Ge,P-GeCl(pyrmPiPr2)2CMe2}] (M = Ag (3), Au (4)). Theoretical calculations have shown that the Ge-M bonds of these complexes are weak and that their strength decreases in the series 2 > 3 > 4.