The facile preparation and structural characterization of [M6{P(SiMe3)2}6] (M = Ag, Cu) is reported. These complexes show limited stability towards solvent loss at ambient temperature; however, N-heterocyclic carbene (NHC) ligands were used to synthesize more thermally stable metal-silylphosphido compounds. 1,3-Di-isopropylbenzimidazole-2-ylidene ((i)Pr2-bimy) and 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene (IPr) are found to be excellent ligands to stabilize silylphosphido-copper compounds that show higher stability when compared to [Cu6{P(SiMe3)2}6].