Effect of Ring Substituents on Formation Rates for Vanadium−Arene Clusters

Vanadium−arene complexes, V n (arene) m (arene = benzene (C 6 H 6 ), toluene (C 6 H 5 CH 3 ), and fluorobenzene (C 6 H 5 F)), were synthesized by the reaction of laser-vaporized vanadium atoms with arene vapor. Both the analysis of the mass spectra and the measurements of their ionization energies indicate that both V n (C 6 H 5 CH 3 ) m and V n (C 6 H 5 F) m clusters take a multiple-decker sandwich structure similar to the structure of V n (C 6 H 6 ) m clusters. The relative reactivity between benzene and toluene toward vanadium was also determined; toluene is 4 times as reactive as benzene for V 1 (C 6 H 5 CH 3 ) 1 /V 1 (C 6 H 6 ) 1 production and 2 times for V 1 (C 6 H 5 CH 3 ) 2 /V 1 (C 6 H 6 ) 2 production because of reactivity enhancement of the electron-donating ring substituent. In the case of the V n (C 6 H 5 F) m cluster, it is found that the electron-withdrawing ring substituent of fluorobenzene results in much less reactivity than is observed for benzene and toluene.