THE REACTIVITY OF A BIS(MU-DIPHENYLPHOSPHIDO) DICYCLOPENTADIENYL DIMOLYBDENUM COMPLEX WITH AN ELECTRON-WITHDRAWING RING SUBSTITUENT

The synthesis of [(eta(5)-C5H4CO2Me)(2)Mo-2(CO)(6)] (1), a bis(cyclope ntadienyl) dimolybdenum complex with an electron withdrawing ring subs tituent, from the reaction of Mo(CO)(6) and [Na(C5H4CO2Me)] is describ ed. Complex 1 reacts thermally with P2Ph4 to form the bis(mu-diphenylp hosphido) complex [(eta(5)-C5H4CO2Me)(2)Mo-2(mu-PPh2)(2)(CO)(2)] (2). Air oxidation of 2 gives trans-[(eta 5-C5H4CO2Me)(2)-Mo-2(mu-PPh2)(2)( O)(CO)] (3a) and the corresponding cis-isomer 3b. The reactions of 3a and of the corresponding unsubstituted cyclopentadienyl complex [(eta( 5)-C5H5)(2)Mo-2(mu-PPh2)(2)(O)(CO)] (4) with [NO] [BF4], which yield r espectively the nitrosyl substituted dimolybdenum complexes (eta(5)-C5 H4CO2Me)(2)Mo-2(mu-PPh2)(2)(O)(NO)][BF4] (5) and [(eta(5)-C5H5)(2)Mo-2 (mu-PPh2)(2)(O)(NO)][BF4] (6), are described. Single crystal X-ray dif fraction was used to determine the molecular structures of 1 (which cr ystallises in the monoclinic space group P2(1)/c with a=9.811 (4), b=1 2.109 (2), c=9.919 (3) Angstrom, beta=110.00 (3)degrees and Z=2), 2 (w hich crystallises in the triclinic space group P (1) over bar, a=13.36 4 (4), b=14.535 (4), c=10.576 (2) Angstrom, alpha=91.33 (2), beta=94.9 4 (2) gamma=108.92 (2)degrees and Z=2) and 3a (which crystallises in t he monoclinic space group P2(1)/c with a=12.436 (2), b=15.300 (3), c=2 0.395 (4) Angstrom, beta=111.59 (3)degrees and Z=4).