A valence-delocalised osmium dimer capable of dinitrogen photocleavage: ab initio insights into its electronic structure

Vera Krewald, Leticia González

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)
38 Downloads (Pure)

Abstract

The search for molecular catalysts that efficiently activate or cleave the dinitrogen molecule is an active field of research. While many thermal dinitrogen cleavage catalysts are known, the photochemical activation of N 2 has received considerably less attention. In this paper, the first computational study of the osmium dimer [Os (II,III) 2(μ-N 2)(NH 3) 10] 5+, which was shown to be capable of dinitrogen photocleavage, is presented. Despite its deceptively simple geometry, it has a complex electronic structure with a valence-delocalized and electronically degenerate ground state. Using multiconfigurational methods, the electronic structure at the ground state geometry and along the dinitrogen cleavage coordinate was investigated. The results indicate that an unoccupied molecular orbital with σ-bonding character between osmium and μ-N atoms and σ-antibonding dinitrogen character is most affected by N–N distance elongation. This implies that a lower barrier for thermal or photochemical N 2 activation in linear M-N-N-M complexes can be achieved by lowering the energetic separation between this unoccupied orbital and the HOMO, representing a specific target for future catalyst design.

Original languageEnglish
Pages (from-to)5112-5123
Number of pages13
JournalChemistry - A European Journal
Volume24
Issue number20
Early online date17 Nov 2017
DOIs
Publication statusPublished - 6 Apr 2018

Keywords

  • ab initio calculations
  • mixed-valent compounds
  • nitrogen fixation
  • osmium
  • transition metals

ASJC Scopus subject areas

  • Catalysis
  • Organic Chemistry

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