Single imido tungsten imido precursors are described for the deposition of tungsten nitride on a substrate by processes such as metal organic chemical vapor deposition. The precursors may be employed to form diffusion barrier layers on microelectronic devices. A method for forming tungsten nitride layers includes the steps of providing a tungsten imido species having the formula LyW(NR)Xn, where R is a carbon containing group, y is an integer between 0 and 5, n is an integer between 0 and 4 and Ly and Xn are selected from the group of non-imido ligands. The single imido tungsten imido species is flowed to a surface of a substrate where the single imido tungsten imido species decomposes to form a tungsten nitride layer.