The [Ru(N3)2(PPh3)(py)3] and [Ru(N3)2(PPh3)2(β-pic)2] complexes have been prepared and studied by IR, NMR, UV–Vis spectroscopy and X-ray crystallography. The complexes were prepared in the reactions of [RuCl2(PPh3)3] with pyridine, β-picoline and NaN3 in methanol solutions. The electronic structures of the obtained complexes have been calculated using the DFT/TD-DFT method. The trans effect of triphenylphosphine on the pyridine molecule has been studied using NBO and molecular orbital terms, and impact of the acceptor properties of the halide/pseudohalide co-ligands was indicated.