Intramolecular Ligand Exchange in Phosphoranes. A Comparison of Berry Pseudorotation and Turnstile Rotation

Julianna A. Altmann, Keith Yates, I. G. Csizmadia

Research output: Contribution to journalArticle

52 Citations (Scopus)

Abstract

Ab initio calculations employing a large basis set have been carried out for a model molecule (PH5) to investigate the reaction profiles corresponding to the Berry pseudorotation (BPR) and the turnstile rotation (TR), these being the mechanistic possibilities proposed for the intramolecular ligand exchange in phosphoranes. Results suggest that the BPR should be a concerted process involving a very low (1.95 kcal/mol) energy of activation. In contrast, the TR process, which could be the active reaction coordinate for structurally restricted systems, may be better described as a sequential type process with a considerably larger (10.05 kcal/mol) overall activation energy. Examination of the reaction hypersurface in the vicinity of the Cs and C, points revealed that only the C geometry represents a genuine saddle point. This implies that, at least in the case of structurally flexible phosphoranes as modeled by PHH5, the TR should be regarded as a vibrationally excited mode of the BPR.

Original languageEnglish
Pages (from-to)1450-1454
Number of pages5
JournalJournal of the American Chemical Society
Volume98
Issue number6
DOIs
Publication statusPublished - Mar 1 1976

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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