BINUCLEAR CYCLOPENTADIENYL CARBONYL-COMPLEXES OF MOLYBDENUM(I) WITH BIDENTATE PHOSPHORUS BRIDGING LIGANDS - SYNTHESIS AND REACTIONS LEADING TO NEW DIMOLYBDENUM(II) COMPLEXES

The compounds (mu-P-P)Mo2Cp2(CO)4 (Cp = eta-5-C5H5; P-P = Ph2PCH2PPh2, dppm; (EtO)2POP(OEt)2, tedip) were prepared from Mo2Cp2(CO)4 (Mo=Mo) and dppm or tedip, respectively. In the reaction with tedip, the compound (mu-(EtO)2PO)(mu-P(OEt)2)Mo2Cp2(CO)4 was also isolated. The dppm-bridged compound reacted with different electrophiles to give new dimolybdenum(II) complexes. Thus, reaction with HBF4 or [Ipy2]BF4 (py = pyridine) gave the compounds [(mu-X)(mu-dppm)Mo2Cp2(CO)4]BF4 (X = H, I), whereas reaction with the electrophiles I2 or HgCl2 gave (X)(CO)2CpMo(mu-dppm)MoCp(CO)2(Y) (X = Y = I; X = ClHg, Y = Cl). The related (mu-dppm)Mo2Cp2(CO)4Cl2 could be obtained by treatment of MoCp(CO)3Cl with dppm)Mo2Cp2(CO)4], which was used in situ to obtain new dimolybdenum(II) species. Protonation of the anion with NH4PF6 gave the dihydrido complex (mu-dppm)Mo2Cp2(CO)4H2, and treatment with CH2I2 or (ClCuPPh3)4/Ph4AsCl led to (ICH2)(CO)2CpMo(mu-dppm)MoCp(CO)2I or to the trinuclear anion Ph4As[(mu-CuPPh3)(mu-dppm)Mo2Cp2(CO)4], respectively. The presence of different isomers in some of the compounds described and the influence of the solvent and temperature on the corresponding equilibria are discussed.