On the pathway of the eta(1)-eta(5) migration of a Cp* ligand

The thermolysis and photolysis, respectively, of the phosphinidene complex [Cp*P{W(CO)(5)}(2)] 1 in the presence of MeC=CMe leads to the three-membere d heterocycle [(eta(2)-CH2C5Me4)W(CO)(4)C{(CH3)CH(CH3)}PW(CO)(5)] 4 with an unusual eta(2)-coordinated CH2C5Me4 ligand formed by a 1,4-sigmatropic hyd rogen shift; the crystal structure and the spectroscopic data of 4 are disc ussed.