This invention relates to organometallic precursor compounds represented by the formula (Cp(R′)x)yM(H)z-y, a process for producing the organometallic precursor compounds, and a method for depositing a metal and/or metal carbide layer, e.g., Ta metal and/or TaC layer, on a substrate by the thermal or plasma enhanced disassociation of the organometallic precursor compounds, e.g., by CVD or ALD techniques. The metal and/or metal carbide layer is useful as a liner or barrier layer for conducting metals and high dielectric constant materials in integrated circuit manufacturing.