Complexes of group 13 metal halides with pyridine-type ligands (pyridine, pyrazine, and 4, 4´-bipyridine) have molecular, polymeric, or ionic structures containing metal atoms with a coordination number of 4, 5, or 6 depending on the component ratio, the acceptor ability of the halide, the donor ability and the coordination mode of the ligand. The strongest donor-acceptor bond is formed in the 1 : 1 molecular complexes, and their transition to the gas phase is energetically most favorable. The acceptor ability of Lewis acids in the complexes decreases in the series AlCl₃ > AlBr₃ > GaCl₃ > GaBr₃ > GaI₃. The stability of the complexes with respect to homogeneous dissociation correlates with the donor proton affinity. Group 13 metal trihalides act as catalysts for the pyrolysis of ligands.