THE SYNTHESIS OF DINUCLEAR MOLYBDENUM AND TUNGSTEN COMPLEXES WITH THE BRIDGING HETERODIFUNCTIONAL LIGAND C5H4PPH2 - X-RAY CRYSTAL-STRUCTURE OF MO2(MU-C5H4PPH2)(ETA-5-C5H5)(CO)5

The synthesis and some reactions of dinuclear metal-metal bonded complexes of molybdenum and tungsten bridged by the heterodifunctional ligand C5H4PPh2 are reported. The new complexes MoM (mu-C5H4PPh2)(eta5-C5H5)(CO)5 [M = Mo (1a); M = W (1b)], and Mo2(mu-C5H4PPh2)(eta5-C5H4-PPh2)(CO)5 (1c) have been characterized, together with the phosphine substituted derivatives MoM(mu-C5H4PPh2)(eta5-C5H5)(CO)4L [M = Mo, L = PPh2Me (2a); M = Mo, L = P(OMe)3 (2b); M = W, L = PPh2Me (2c)] and the di-bridged complex Mo2(mu-C5H4PPh2)2(CO)4 (3). The molecular structure of Mo2(mu-C5H4PPh2)(eta5-C5H5)(CO)5 (1a) has been determined by X-ray diffraction. Treatment of 1a, 1b and 3 with HBF4 gives the corresponding monoprotonated derivatives 4a, 4b and 5, respectively, in which the proton occupies a bridging site between the metal centres. The new mononuclear complexes Mo(eta5-C5H4PPh2) (CO)3I (6) and Mo(eta5-C5H4PPh2)(CO)2NO (7) have also been prepared.