First mixed valence cerium–organic trinuclear cluster [Ce3(OBut)10NO3] as a possible molecular switch: synthesis, structure and density functional calculations

Abstract

The crystalline trinuclear cerium cluster complex [{(Ce(OBu^t)₂}₂(μ-OBu^t)₃(μ₃-OBu^t)₂{Ce(OBu^t)(NO₃)}] 1 has been obtained in good yield from 2[Ce(OBu^t)₄(thf)₂], [Ce(OBu^t)₃(NO₃)] and Sn(C₅H₃Bu^t ₂-1,3)Me₃ by refluxing in hexane, and was characterised by microanalysis, ¹H NMR, IR and UV–Vis spectra and MS data. Its structure and bonding have been analysed by X-ray diffraction. Density functional calculations were carried out on the model compound 2, in which each OBu^t substituent was replaced by OH, and 3, related to 2 but with OH instead of NO₃. The geometric parameters showed good agreement with experiment. It is concluded that 1 is a mixed valence Ce(III)[Ce(IV)]₂ cluster, that the single f electron is localised on the NO₃-bearing Ce atom, and that excitation of this electron to a low energy alternative state is facile. Hence the cluster may offer potential as an f-electron molecular switch.