Reactions of the dioxomolybdenum(VI) compound, MoCl2O2 with phenylenediamine derivatives the bidentate N-N nitrogen ligands 1-8 (ophenylenediamine, N-phenyl-o-phenylenediamine, 4-Methyl-o-phenylenediamine, 4-Nitro-o-phenylenediamine, p-phenylenediamine, N-phenyl-p-phenylenediamine, 2,6- dichloro-p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, respectively) have been examined under nitrogen in THF solution. The novel dioxomolybdenum complexes were characterized by elemental analysis, FT-IR, 1H-NMR and 13C-NMR spectroscopy. In addition, molecular mechanics and quantum chemical calculations including semi empirical PM3 and DFT methods were carried out to discuss the stability of the compounds.