Anodic oxidation of rhenium in ethanol in the presence of LiCl as a conductive additive results with high yield in
formation of a new oxoethoxide cluster, Re4O4(OEt)12. The structure of the planar centrosymmetric metal–oxygen
core of this molecule is composed of four edge-sharing Re(V)O6 octahedra. Eight electrons are available for the
formation of metal-metal bonds indicated by five relatively short Re-Re distances within the Re4-rhombus, a
“planar butterfly” type cluster. The theoretical calculations are indicating relatively low contribution of metal-metal
bonding in the stability of the core. The stability of the +V-oxidation state, unusual for rhenium alkoxides can be
at least partially attributed to the size effects in the packing of ligands. The X-ray powder study indicates that
treatment of Re4O4(OEt)12 in ambient atmosphere rapidly transforms it into a mixed-valence derivative
Re4O6(OEt)10swith a structure related to the earlier investigated cluster Re4O6(OiPr)10. Thermal decomposition of
the latter rhenium oxoethoxide results in reduction to rhenium metal at as low temperatures as 380 °C, producing
aggregates of metal nanoparticles with the average size of 3 nm.
2008. Vol. 47, 1295-1300 p.