Comparative study of diastereoisomer interconversion in chiral BINOL-ate and diamine platinum complexes of conformationally flexible NUPHOS diphosphines

Simon Doherty, C.R. Newman, Rakesh Rath, J.A. Van Den Berg, Christopher Hardacre, Mark Nieuwenhuyzen, J.G. Knight

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

A thorough and detailed study of diastereointerconversion in the chiral platinum complexes [(NUPHOS)Pt{(S)-BINOL}] (3a-e) has been undertaken and compared with the results of a similar study with [(BIPHEP)Pt{(S)-BINOL}]. Rate data revealed that this process obeys first-order relaxation kinetics, and rate constants for conversion of the minor to the major diastereoisomer have been obtained. Eyring analysis of the data gave DeltaH(double dagger) and DeltaS(double dagger) values of 22-25 kcal mol(-1) and -1 to -16 eu, respectively. In combination with computational analysis, these studies indicate that atropinversion most likely occurs via an on-metal pathway involving a planar seven-membered transition state. Substitution of (S)-BINOL for (S,S)-DPEN results in a marked reduction in the barrier to atropinversion; a DeltaH(double dagger) value of 17 kcal mol(-1) has been determined for the conversion of delta-[(Ph-4-NUPHOS)Pt{(S,S)-DPEN}]Cl-2 to lambda-[(Ph-4-NUPHOS)Pt{(S,S)-DPEN}]Cl-2, which could indicate that an alternative mechanism operates.
Original languageEnglish
Pages (from-to)1055-1064
Number of pages10
JournalOrganometallics
Volume23 (5)
Issue number5
DOIs
Publication statusPublished - 01 Jan 2004

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Organic Chemistry

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