Enhanced thermal stability of Cu-silylphosphido complexes via NHC ligationElectronic supplementary information (ESI) available: PXRD patterns for 1 and 2; 1H NMR and IR spectra for 3 and 4. CCDC 1403314 for 1, 1403315 for 2, 977980 for 3 and 1403316 for 4. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt02040a

The facile preparation and structural characterization of [M 6 {P(SiMe 3 ) 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 Pr 2 -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 [Cu 6 {P(SiMe 3 ) 2 } 6 ]. The thermal stability of the Cu-P(SiMe 3 ) 2 moiety can be enhanced via N-heterocyclic carbene ligation.