Electrochemical Synthesis, Structural Characterization, and Decomposition of Rhenium Oxoethoxide, Re4O4(OEt)12. Ligand Influence on the Structure and Bonding in the High-Valent Tetranuclear Planar Rhenium Alkoxide Clusters
- 26 January 2008
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 47 (4) , 1295-1300
Abstract
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)10—with 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.Keywords
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