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(2)PPh(2))] and its ethyl substituted derivative [Mo(CO)(4)(MeImCHEtPPh(2))]

The complex [Mo(CO)(4)(PN)] 1 was synthesized by refluxing [Mo(CO)(6)], wit h 2-(diphenylphosphinomethyl)-1-methylimidazole (PN) in ethanol in the pres ence of NaBH4. The co-ordinated PN is selectively deprotonated to afford a carbanion [Mo(CO)(4)(MeImCHPPh(2))](-) 1a when 1 is treated with strong bas es such as methyllithium or n-butyllithium at room temperature. The carbani on 1a readily reacted with deuterium oxide, methyl iodide, ethyl iodide, al lyl bromide, and trimethylsilyl chloride to give [Mo(CO)(4)(MeImCHRPPh(2))] (R = D 2, Me 3, Et 4, CH2=CHCH2 5 or SiMe3 6). Treatment of 1a with chloro diphenylphosphine and benzoyl chloride gave the corresponding derivatives [ Mo(CO)(4){MeImCH(PPh2)(2)}]. 0.5H(2)O 7 and [Mo(CO)(4){MeImCH(COPh)PPh2}]. H2O 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)PPh2}]. 0.5H(2)O 9 instead of an acetyl derivative. The H-1 and P-31 NMR spectra indicated the presence of two geometric isomers (Z and E) for complex 9. All of these complexes were fully characterized by IR, H-1 and P-31 NMR. The molecular structures of complex 1 and its ethyl substituted derivative 4 have also be en studied by single crystal X-ray analyses.