It has been found that (OC)5WPPh2CH2CH-(PPh2)2 (3) and (OC)5WPPh2CH(PP
h2)CH2PPh2 (9) exist in equilibrium in solution at room temperature. T
his isomerization is the first experimental evidence for the exchange
of terminal and coordinated phosphorus groups in pentacarbonyl complex
es of group 6 metals.