Reactivity of co-ordinated ligands. Part XVII. Heptafulvene complexes of chromium, molybdenum, and tungsten

Abstract

Heptafulvene complexes of tricarbonylchromium, RR′C₈H₆Cr(CO)₃(R = H, R′= H, Me, or Ph; R = Me, R′= Me or Et; R = Ph, R′= Me or Ph), tricarbonylmolybdenum RR′C₈H₆Mo(CO)₃(R = Ph, R′= Me or Ph), and tricarbonyltungsten RR′C₈H₆W(CO)₃(R = Me, R′= Et; R = Ph, R′= Me or Ph) have been prepared. Their reactivity towards electrophilic reagents has been investigated and is different to that of the analogous derivatives of tricarbonyliron. Thus where as addition or substitution occurs on the ring system of the iron complexes these complexes resemble free heptafulvenes in showing exclusive reactivity at the exocyclic double bond. The complexes function as a convenient source of the reactive heptafulvene for in situ reactions with dienophiles.