Driving Electrons to Anti-Bonding States: On the Synthesis of New Niobium Cluster Chlorides by Electrochemical Lithium Intercalation

Abstract

AbstractThe lithium intercalation chemistry of LiNb6Cl15, a 16 e− Nb-cluster, has been explored in order to obtain new Nb-cluster compounds. As a result, three different phases have been detected. Full de-intercalation of lithium produces Nb6Cl15, a new 15 e− Nb-cluster. The oxidation reaction is reversible since lithium can be intercalated again to produce the parent LiNb6Cl15. On the other hand, intercalation of lithium into LiNb6Cl15 seems to proceed through two single phases with the following stoichiometries: Li1.5Nb6Cl15 and Li3Nb6Cl15. For these two compositions the extra electrons (0.5 and 2 respectively/formula) should enter the eg* molecular orbitals arising from Nb-Nb interactions inside the cluster. The reductions of LiNb6Cl15 leading to these two new electron-rich Nb-cluster are reversible as detected by chronopotentiometry.