Solvent-controlled formation of η3-butadienyl or η3-allyl group 6 transition metal complexes in water or alcohols

Preparation of acyl chloride, ester, amide or thioester-substituted η3-butadienyl complexes of the type [MCl(CO)2(η3-CH2C(COXR)CCH2)(L2)] (M=Mo,W; XR=Cl, OR, NHR, SR; L2=1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline) from 1,4-dichloro-2-butyne and Ph4P[MCl(CO)3(L2)] in water resulted in improved yields (M=Mo) and recycling of reagents. Whilst analogous reactions in anhydrous methanol to yield either substituted η3-butadienyl (XR=OR) or η3-allyl [MoCl(CO)2(η3-CH2C(CO2R)C(OR)Me)(phen)] were dependent upon the presence of organic bases or ethers, reactions in propanol or butanol gave the η3-butadienyl complexes only. Possible mechanisms are discussed. Halide extraction from ester or amide butadienyl complexes in hydroxylic solvents gave highly reactive cations of the type [Mo(CO)2(η3-butadienyl)(phen)(solvent]+, and carboxylate products were obtained by displacement of metal-bound solvent by glucuronate or hydroxybutyrate ions.