A mixture of the tungsten allylimido complexes Cl-4(RCN)W(NC3H5) (3a, R = CH3 and 3b, R = Ph) was tested as a single-source precursor for growth of tungsten nitride (WNx) or carbonitride (WNxCy) thin films. Films deposited from 3a,b below 550 degrees C contained amorphous beta-WNxCy, while those deposited at higher temperatures were polycrystalline. Film growth rates from 3a,b ranged from 5 to 10 angstrom/min over a temperature range of 450-650 degrees C, and the apparent activation energy for film growth was 0.15 eV. A plot of the E. values for deposition from Cl-4(RCN)W(NR') [R' = Ph, Pr-i, allyl] against the N-C imido bond strengths for the analogous amines R'NH2 is linear, implicating cleavage of the N-C bond as the rate-determining step in film growth. The correlation of mass spectral fragmentation patterns for Cl-4(RCN)W(NR') with film properties such as nitrogen content supports the significance of facile N-C bond cleavage in film growth.