Ab initio study of bond characteristics and magnetic properties of mixed-sandwich VnBzmCpk clusters.

Ab initio spin-polarized density functional calculations have been performed on mixed-sandwich clusters V(n)Bz(m)Cp(k) (n = 1-3, m + k = n + 1, Bz = benzene, Cp = cyclopentadienyl) to study their size-dependent and composition-dependent structural, electronic, and magnetic properties. All of the mixed-sandwich clusters are thermodynamically stable with larger binding energies than those of V(n)Bz(n+1). Furthermore, the binding energies of V(n)Bz(m)Cp(k) show clear dependence on the number of Cp rings as well as on the relative positions of Cp (or Bz) rings inside of the molecules. More interestingly, the replacement of a Bz with a Cp ring in V(n)Bz(n+1) brings one net spin into the cluster, which is attributed to the transfer of one minority ddelta electron from the V atom to its adjacent Cp ligand. In addition, the ferromagnetism stability of V(n)Bz(n+1) is significantly enhanced upon Cp replacement.