Reaction of [PPh(2)M(CO)(5)]Li salts (M = Cr or W) toward tungstenocene dichloride occurs via a cyclopentadienyl ring substitution and yields the corresponding binuclear compounds (eta(5)-C5H5)[eta(5)-C(5)H(4)PPh(2)M(CO)(5)]W(H)Cl, 2. They react with LiAlH4 to give the corresponding dihydride complexes (eta(5)-C5H5)[eta(5)-C(5)H(4)PPh(2)M(CO)(5)]WH2, 3. These species have been proven to be photosensitive leading to the cyclic heterobimetallic (eta(5)-C5H5)[eta(5)-C(5)H(4)PPh(2)M(CO)(4)]W(mu-H)H compounds, 4; analytical data and spectroscopic measurements on complexes 4 indicate that a hydride group functions as a bridging ligand. Crystals of 4a (M = Cr) were obtained as red needles, grown from toluene solution. An isotropic refinement of only 1243 data (F > 5 sigma(F)) from a low resolution data set (3707 data, d(min) = 0.9 Angstrom) indicated significant systematic error. Thus it was possible only to ascertain that the connectivity of the non-hydrogen atoms is not inconsistent with the model proposed from solution NMR and that the Cr ... W separation of 3.30 Angstrom precludes a direct Cr-W bond. 4a crystallizes in space group Pbca (No. 61), with a = 19.693(8) Angstrom, b = 20.34(1) Angstrom, c = 11.695(5) Angstrom, V = 46823 Angstrom(3), and Z = 8. Further information on this preliminary structure determination is provided in the Supporting Information. These reactions have been investigated with stereochemical factors in mind using the ring substituted tungtenocene complex (eta(5)-C(5)H(4)Me)(2)WCl2; the 1-3 regioselectivity of the ring disubstitution reaction is proposed on the basis of H-1 NMR experiments. The temperature dependent relaxation time measured between 295 and 213 K by the inversion recovery method makes it possible to determine a proton-proton distance between the two H ligands of 2.0 Angstrom in 4’a.