The [RuCl3(PPh3)(2)(HPz)]center dot C6H6 and t,t,t-[RuCl2(PPh3)(2)(HPz)(2)]center dot 2C(6)H(6) complexes have been obtained in the reaction of [RuCl3(PPh3)(3)] with pyrazole, and characterized by IR, UV-Vis and NMR spectroscopies. The crystal and molecular structures of the complexes have been determined by X-ray crystallography. Based on the molecular geometries, electronic structures and UV-Vis spectra of the complexes have been calculated using the OFT and TO-OFT methods. A discussion on the stability of the two isomers of the [RuCl2(PPh3)(2)(HPz)(2)] complex, based on an analysis of overlap partial density-of-state diagrams, has been presented. The combined interactions between pyrazole, chloride and PPh3 ligands stabilize the cis, cis, trans form of the [RuCl2(HPz)(2)(PPh3)(2)] complex, as was unequivocally exhibited.