Preparation, Mechanism, and Structural Study of Group 6 Transition Metal 2-Substituted η3-Butadienyl Complexes: Crystal Structure of [WCl(CO)2{η3-CH2C(COSBun)CCH2}(1,10-phenanthroline)

Abstract

The complexes [WCl(CO)2(η3-CH2C(COX)CCH2)L2] (X = Cl; L2 = 2,2‘-bipyridyl, 1,10-phenanthroline) (1) containing a 2-substituted butadienyl ligand were isolated from reactions of Ph4P[WCl(CO)3L2] and excess 1,4-dichlorobut-2-yne in chlorinated solvents. Spectroscopic evidence supports analogous reactions for the chromium analogue. Addition of 1 to alcohol, amine, or thiol (HX) gave good yields of the related ester (X = OMe), amide (X = NEt2), or thiolate (X = SBun) complexes, respectively. Mechanisms and supporting evidence for the formation of 1 and the ester complex are proposed and discussed. Some differences in reactivity of Ph4P[MCl(CO)3L2] with 1,4-dichlorobut-2-yne in methanol are reported for M = Mo and M = W. The structure of [WCl(CO)2(η3-CH2C(COSBun)CCH2)(1,10-phenanthroline)] was confirmed by single-crystal X-ray diffraction analysis.