General Syntheses of (RPPh2)Mo(CO)5and (RDBP)Mo(CO)5Complexes from Ph2PLi and DBPLiviaSingle Electron Transfer Catalysis

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Abstract
Lithium diphenylphosphide and lithium dibenzophospholide (LiDBP) react rapidly at ambient temperature in dry tetrahydrofuran solutions with Mo(CO)6 to form [(LiPPh2)Mo(CO)5] and [(LiDBP)Mo(CO)5], respectively. These two compounds may be alkylated with halocarbons (RX) or protonated with acetic acid in the same reaction vessel to give good yields of (RPPh2)Mo(CO)5, (HPPh2)Mo(CO)5, (RDBP)Mo(CO)5 or (HDBP)Mo(CO)5. These compounds have been characterized by elemental analyses, physical properties, 1H, 13C{1H}, 31P{1H} and 95Mo NMR spectroscopy and infrared spectroscopy. Three hydrogen shift isomers are formed in the reaction of [(LiPPh2)Mo(CO)5] with ClCH2C[tbnd]CH, viz, (HC[tbnd]CCH2PPh2)Mo(CO)5, (H2C=C=CHPPh2)Mo(CO)5 and (CH3C[tbnd]CPPh2)Mo(CO)5. The crystal structures of the two latter compounds and (l-trans-2-buteneyldibenzophosphole)molybdenum pentacarbonyl, (crotyl DBP)Mo(CO)5, (at 173K) have been determined. These compounds crystallize in the monoclinic P21/n, triclinic P[ibar], and triclinic P space groups respectively, in unit cells with the following dimension: a = 16.355(3)Å, b = 8.114(1)Å, c = 16.617(3)Å, β = 113.09°, V = 2028.5(6)Å3, calc = 1.507 g cm−3, Z = 4; a = 8.253(1)Å, b = 10.497(2)Å, c = 11.933(2)Å, α = 89.89(1)°, β = 83.61(1)°, γ = 77.03(1)°, V = 1000.8(4)Å3, calc = 1.527 g cm−3, Z = 2 and a = 7.894(2)Å, b = 10.137(2)Å, c = 13.959(2)Å, α = 76.17(1)°, β = 81.42°(1)°, γ = 68.17(1)°, V = 1004.6(4)Å3, calc = 1.568 g cm−3, Z = 2, respectively. Least-squares refinements converged to R(F) = 0.0494, 0.0425, and 0.0406 for 2655, 3333 and 2612 independent (I > 2[sgrave](I), F > 4[sgrave](F), and I > 2[sgrave](I)) reflections, respectively. Spectroscopic data indicate that the RDBP ligands are better π-acceptors than the RPPh2 ligands, but show little differentiation among any of the alkyl substituents.