DFT studies on gas-phase reactions mechanism of (M2O5)(m=1,2)(+) (M = V, Nb, Ta) and C2H4

The reaction mechanisms of group V transition metal oxide cations(M2O5)+m=1,2(M=V,Nb,Ta) with ethylene were studied by density functional theory with BP86 method.For the reaction(M2O5)+m+C2H4→(M2O5)m-1M2O+4+C2H4O,the bond V-O was broken after the transition state and the oxygen transfer happened.It has both cis and trans transition structures for the reaction of V2O+5 and C2H4,the path with the trans transition structure was energetically favorable.The calculation results show that when it reacted with C2H4,the(V2O5)+m was highly exothermic,but the(M2O5)+m(M=Nb,Ta) were slightly or even not exothermic.This is well in line with the experimental results.The different reactivity of the group V transition metal oxide cluster ions is attributed to the different bond strength of the metal-oxygen bonds.