EFFECT OF RING SUBSTITUENTS ON FORMATION RATES FOR VANADIUM-ARENE CLUSTERS

Vanadium-arene complexes, V-n(arene)(m) (arene = benzene (C6H6), tolue ne (C6H5CH3), and fluorobenzene (C6H5F)), were synthesized by the reac tion of laser-vaporized vanadium atoms with arene vapor. Both the anal ysis of the mass spectra and the measurements of their ionization ener gies indicate that both V-n(C6H5CH3)(m) and V-n(C6H5F)(m) clusters tak e a multiple-decker sandwich structure similar to the structure of V, (C6H6)(m) clusters. The relative reactivity between benzene and toluen e toward vanadium was also determined; toluene is 4 times as reactive as benzene for V-1(C6H5CH3)(1)/V-1(C6H6)(1) production and 2 times for V-1(C6H5CH3)(2)/V-1(C6H6)(2) production because of reactivity enhance ment of the electron-donating ring substituent. In the case of the V-n (C6H5F)(m) cluster, it is found that the electron-withdrawing ring sub stituent of fluorobenzene results in much less reactivity than is obse rved for benzene and toluene.