Preparation, crystal structures and spectroscopic properties of chloro(pentane-2,4-dionato){1,1,1- tris(dimethylphosphinomethyl)ethane}chromium(III), -cobalt(III) and -rhodium(III) hexafluorophosphate: Comparison of the M-P, M-Cl and M-O (M = Cr, Co and Rh) bond lengths among the three MIII complexes

Takayoshi Suzuki, Takeshi Imamura, Sumio Kaizaki, Kazuo Kashiwabara

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Three metal(III)-tripodal tridentate phosphine complexes of the formula [MCl(acac)(tdmme)]PF6, where M = Cr, Co or Rh; acac = pentane-2,4-dionate; tdmme = 1,1,1 -tris(dimethylphosphinomethyl)ethane, were prepared and their molecular and crystal structures and spectroscopic properties examined. All the complexes crystallized in an isomorphous space group P212121, which is indicative of spontaneous resolution of the enantiomeric pair. The Cr-P bond lengths in [CrCl(acac)(tdmme)]PF6 (average 2.437 Å) are remarkably longer than the corresponding Co-P (average 2.201 Å) and Rh-P (average 2.252 Å) ones. The longer and therefore the weaker Cr-P bonds may explain the relatively weak trans influence of the -PMe2 group in [CrCl(acac)(tdmme)]PF6; among the three MIII complexes, the elongation of M-O bond lengths in [MCl(acac)(tdmme)]PF6 from those in [M(acac)3] has been found to be CrIII (0.016 Å) < CoIII (0.059 Å) < RhIII (0.096 Å), indicating a much weaker trans influence of the -PMe2 group in the CrIII complex than in the COIII and RhIII complexes. The first d-d transition band of [CrCl(acac)(tdmme)]+ was observed at 18590 cm-1. This is appreciably smaller than the corresponding band of the CIII complex at 20960 cm-1, suggesting the ligand-field strength of tdmme is fairly weak in the CrIII complex. The ligand-field strength Δ and the Racah's β parameters of [CrCl(acac)(tdmme)]+ were also discussed.

Original languageEnglish
Pages (from-to)835-841
Number of pages7
JournalPolyhedron
Volume21
Issue number8
DOIs
Publication statusPublished - Apr 15 2002
Externally publishedYes

Keywords

  • Acetylacetonate complexes
  • Chromium(III) complexes
  • Crystal structures
  • Ligand-field strength
  • Trans influence
  • Tripodal tridentate phosphine

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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