Monomer-dimer equilibria of oxo/imido complexes of heptavalent rhenium: Theoretical and spectroscopic investigations

Philip Gisdakis, Notker Rösch, Éva Bencze, Janos Mink, Isabel S. Gonçalves, Fritz E. Kühn

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Mixed oxo/imido derivatives of methyltrioxorhenium(VII) form dimers in the solid state at ambient temperature. Density-functional calculations show that the dimerization is exothermic. The most stable derivatives were calculated to display a pseudo trigonal-bipyramidal coordination with two bridging oxygen centers and the methyl groups in a trans arrangement. This configuration is energetically more favored than a cis arrangement of the methyl groups and a pseudo square-pyramidal structure at the metal centers. In the case of methyltrioxorhenium(VII), the dimerization is slightly endothermic, even for the optimal dimeric structure, so that dimers cannot be isolated. However, there is evidence for the transient existence of oxygen bridges between methyltrioxorhenium(VII) in solution. For mixed imido/oxo species, oxygen bridging is observed in all cases of dimerization; results of thermogravimetric/mass spectrometric studies demonstrate that these bridging dimers are weakly bound. From vibrational spectroscopic analysis, there is no evidence for nitrogen-bridged homologues. The density-functional calculations show that imido groups form bridges only in the case of sterically undemanding ligands. However, these complexes are too unstable to be isolated.

Original languageEnglish
Pages (from-to)981-991
Number of pages11
JournalEuropean Journal of Inorganic Chemistry
Issue number4
DOIs
Publication statusPublished - Jan 1 2001

Keywords

  • Density-functional calculations
  • Imido ligands
  • Oxygen bridges
  • Rhenium
  • Transition states

ASJC Scopus subject areas

  • Inorganic Chemistry

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