Density functional theory in form of B3LYP functional has been employed to predict structural, spectral, and thermodynamic characteristics of single-source precursors R3MYH3 and resulting intermediates in the processes of Chemical Vapor Deposition of A(m)B(v). Donor-acceptor bond strength in the source precursor may be used as a criterion to distinguish between two principal CVD mechanisms. Radical reactions dominate in case of precursors with weak donor-acceptor bond (less than or equal to 50 kJ mol(-1)), while for strongly bonded species (greater than or equal to 80 kJ mol(.1)) association processes are essential under low temperature-high pressure conditions (including laser-assisted CVD). Preserving of the metal-nitrogen bond in the gas phase during CVD process (800-1000K) opens the perspective of design of the novel single-source precursors (ring and cluster compounds) for the stoichiometry controlled CVD of nitrides, doped by the rare-earth elements. A mechanism of the carbon contamination of the nitrides with high temperature formation of M, N, C-containing ring intermediates is also suggested and discussed.