The p-tolyldiazenido ruthenium(II) complexes [RuCl3(PPh3)2(N2PhCH3)]·CH3OH (1), [RuCl3(PPh3)(N2PhCH3)(HPz)] (2) and [RuCl3(PPh3)(N2PhCH3)(Im)]·CH3OH (3) were synthesized and characterized by IR, 1H, 13C, 31P NMR, electronic absorption and emission spectroscopy, and X-ray crystallography. In the molecular structure of complex (1) some π–π stacking interactions are observed, whereas in the structure of the imidazole complex (3) graph set analysis shows intermolecular hydrogen bonded rings. The electronic structures of the complexes were calculated by DFT based on their crystal structures. The spin-allowed singlet–singlet electronic transitions of the complexes were calculated by time-dependent DFT and the UV–Vis spectra have been discussed on this basis. The emission properties of the complexes were also studied.