Kinetics of substitution atcis-tetracarbonylbis(4-methylpyridine)-tungsten(0)

Summary Rate constants have been obtained for reactions ofcis-tetracarbonylbis(4-methylpyridine)tungsten(0),cis-[W(CO)₄(4Mepy)₂], with 1, 10-phenanthroline, 2,2-bipyridyl, and related diimine ligands in toluene solution at 298.2K. Effects of varying the nature and concentration of the entering ligand, and of addition of 4-methylpyridine, indicate the operation of a limiting dissociative (D) mechanism. This is confirmed by the establishment of an activation volume of + 8 cm³ mol^–1, in toluene at 298.2K.