Evidence for the fluxionality and structure in solution of intermediates of the type W(CO) 4(L) (L = lewis base)

Abstract

Evidence based on amine substitution reactions in W(CO) 4(tmpa) (tmpa = N, N, N′, N′-tetramethyl-l,3-diaminopropane) and cis-(C 5H 10NH)(PPh 3)W(CO) 4 with PPh 3 and 13CO indicates (a) that the square pyramidal [W(CO) 4PPh 3] intermediate arising from amine dissociation is fluxional, and (b) that the intermediate containing PPh 3 in the equatorial plane of the square pyramid is thermodynamically more stable than that containing PPh 3 in the axial position.