The new complexes [M-2(CO)(10)(mu-R2P(S)P(S)R-2)] (M = Mo, W: R = Me, Et, n-Pr, n-Bu), (1a)-(1d) and (2a)-(2d) [(1a), M = Mo, R = Me, (1b). M = Mo, R = Et; (1c), M = Mo, R = n-Pr, (1d), M = Mo, R = n-Bu. (2a), M = W, R = Me, (2b), M = W, R = Et, (2c), M = W, R n-Pr, (2d). M = W, R = n-Bu] have been prepared by the photochemical reaction of M(CO)(6) with R2P(S)P(S)R-2 (R = Me, Et, n-Pr, n-Bu). The complexes have been characterized by elemental analyses, FT-IR and P-31-[H-1]-NMR spectroscopy and FAB-mass spectrometry. The spectroscopic studies suggest cis-bridging bidentate coordination of the ligand between the two metals.