A convenient method for selective substitutions at the backbone of a co-ordinated imidazolylphosphine P-N ligand. Single crystal X-ray analyses of [Mo(CO)_4(MeImCH_2PPh_2)] and its ethyl substituted derivative [Mo(CO)_4(MeImCHEtPPh_2)]

摘要

The complex [Mo(CO)_4(PN)] 1 was synthesized by refluxing [Mo(CO)_6], with 2-(diphenylphosphinomethyl)-1-methylimidazole(PN) in ethanol in the presence of NaBH_4. The co-ordinated PN is selectively deprotonated to afford a carbainion [Mo(CO)_4(MeImCHPPh_2)]~- 1a when 1 is treated with strong bases such as methyllithium or n-butyllithium at room temperature. The carbanion 1a readily reacted with deuterium oxide, methyl iodide, ethyl iodide, allyl bromide, and trimethylsiyl chloride to give [Mo(CO)_4(MeImCHRPPh_2)](R=D 2, Me 3, Et 4, CH_2=CHCH_2 5 or SiMe_3 6). Treatment of 1a with chlorodiphenylphosphine and benzoyl chloride gave the corresponding derivatives [Mo(CO)_4{MeImCH(PPh_2)_2}].0.5H_2O 7 and [Mo(CO)_4{MeImCH(COPh)PPh_2}].H_2O 8 respectively, both containing an additional free donor site. However, slow addition of acetyl chloride to a tetrahydrofuran solution of 1a gave the O-acetyl enolate derivative [Mo(CO)_4{MeImC=CMe(OCOMe)PPh_2}].0.5H_2O 9 instead of an acetyl derivative. The ~1H and ~(31)P NMR spectra indicated the presence of two geometric isomers (Z and E) for complex 9. All of these complexes were fully characterized by IR, ~1H and ~(31)P NMR. The molecular structures of complex 1 and its ethyl substituted derivative 4 have also been studied by single crystal X-ray analyses.