The crystal structure of MoMe₂(η⁶-C₆H₅)(PPhMe₂)₂ and MoMe₂(η⁶-C₆H₅Me)(PPhMe₂)₂ have been determined from three-dimensional X-ray diffraction data collected by counter methods. The former crystallizes in the monoclinic space group P2₁/n with a= 8.108(4), b= 24.287(8), c= 11.961(5)Å, β= 96.59(4)°, and Z= 4 for D_c= 1.36 g cm^–3. The final R value was 0.035 based on 1 271 independent observed reflections. MoMe₂(η⁶-C₆H₅Me)(PPhMe₂)₂ crystallizes in the triclinic space group P with a= 9.128(2), b= 9.611 (2), c= 14.842(3)Å, α= 105.44(3), β= 93.72(3), γ= 102.47(3)°, and Z= 2 for D_c= 1.35 g cm^–3. The R value was 0·019 for 3 586 observed reflections. The presence of the methyl group on the toluene ligand does not appreciably alter the electronic environment of the molybdenum atom. In the toluene derivative the two Mo–C(σ) bonds average 2.291 (5)Å. The Mo–C(σ) lengths range from 2.250(2) to 2.344(2)Å, and are seen to vary in a pair-wise fashion such that the arene shows a tendency to act as a diene.