Abstract: This invention relates to organometallic compounds represented by the formula (L1)yM(L2)z-y wherein M is a Group 5 metal or a Group 6 metal, L1 is a substituted or unsubstituted anionic 6 electron donor ligand, L2 is the same or different and is (i) a substituted or unsubstituted anionic 2 electron donor ligand, (ii) a substituted or unsubstituted cationic 2 electron donor ligand, or (iii) a substituted or unsubstituted neutral 2 electron donor ligand; y is an integer of 1, and z is the valence of M; and wherein the sum of the oxidation number of M and the electric charges of L1 and L2 is equal to 0; a process for producing the organometallic compounds; and a method for depositing a metal and/or metal carbide/nitride layer, e.g., a tungsten, tungsten nitride, tungsten carbide, or tungsten carbonitride layer, on a substrate by the thermal or plasma enhanced dissociation of the organometallic precursor compounds, e.g., by CVD or ALD techniques.