First mixed valence cerium-organic trinuclear cluster [Ce-3(OBut)(10)NO3] as a possible molecular switch: synthesis, structure and density functional calculations

The crystalline trinuclear cerium cluster complex [{(Ce(OBut)(2)}(2) (mu-OBut)(3) (mu(3)-OBut)(2) {Ce(OBut)(NO3)}] 1 has been obtained in good yield from 2[Ce(OBut)(4) (thf)(2)], [Ce(OBut)(3) (NO3)] and Sn(C5H3Bu2t-1,3) Me-3 by refluxing in hexane, and was characterised by microanalysis, H-1 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 OBut 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.