The formation of gas-phase oligomer compounds in the Cl-Ga-N-H system is considered using hybrid Hartree-Fock/density functional theory and a polarized double-zeta quality basis set, Geometric parameters, vibrational frequencies, and thermodynamic characteristics for the Cl3GaNH3 adduct, its dissociation products GaCln, NHn, (n = 1-3), the amidochlorogallanes [Cl2GaNH2](n) (n = 1-3), their donor-acceptor complexes with GaCl3 and NH3, and the imidochlorogallanes [ClGaNH](n) (n = 1-4,6) have been obtained. Generation of amidochlorogallanes is expected to be viable during laser assisted chemical vapor deposition (CVD) at low temperatures. High-temperature association processes in the gas phase during the CVD of GaN from the Cl3GaNH3 adduct are predicted to be less important, in contrast to previous findings for the aluminum analogue. This difference may be explained in terms of a much lower Ga-N bond energy compared to Al-N in the ring and cluster compounds.