Synthetic, structural, spectroscopic, and electrochemical studies of mixed sandwich Rh(III) and Ir(III) complexes involving Cp* and tridentate macrocycles

Gregory J. Grant, John P. Lee, Monte Helm, Donald G. VanDerveer, William T. Pennington, Jeffrey L. Harris, Larry F. Mehne, David W. Klinger

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Abstract

The syntheses, structures, spectroscopy, and electrochemistry for six Ir(III) and Rh(III) mixed sandwich mononuclear complexes involving tridentate macrocycles and pentamethylcyclopentadienide (Cp*) are reported. The complexes are readily prepared by direct ligand substitution reactions from the dichloro bridged binuclear complexes, [{M(Cp*)(Cl)2} 2]. All complexes have the general formula [M(L)(Cp*)]X 2 (M = Ir(III) or Rh(III), L = macrocycle, X = PF6 - or Cl-) and exhibit a distorted octahedral structure involving three donor atoms from the macrocycle and the facially coordinating carbocyclic Cp* ligand. The complex cations include: [Rh(η 5-Cp*)(9S3)]2+ (1), [Rh(η5-Cp*) (9N3)]2+ (2), [Rh(η5-Cp*)(10S3)]2+ (3), [Ir(η5-Cp*)(9S3)]2+ (4), [Ir(η5-Cp*)(9N3)]2+ (5), and [Ir(η5-Cp*)(10S3)]2+ (6), where 9S3 = 1,4,7-trithiacyclononane, 9N3 = 1,4,7-triazacyclononane, and 10S3 = 1,4,7-trithiacyclodecane. The structures for all six complexes are supported by 1H and 13C{1H} NMR spectroscopy, and five complexes are also characterized by single-crystal X-ray crystallography (complexes 1-5). The 1H NMR splittings between the two sets of methylene protons for both the Rh(III) and Ir(III) 9S3 complexes are much larger (0.4 vs. 0.2 ppm) compared to those in the two 9N3 complexes. Similarly, the 13C{1H} NMR spectra in all four thioether complexes show that the ring carbons in the Cp* ligand are shifted by over 10 ppm down.eld compared to the azacrown complexes. The electrochemistry of the complexes is surprisingly invariable and is dominated by a single irreversible metal-centered reduction near - 1.2 V vs. Fc/Fc+.

Original languageEnglish
Pages (from-to)629-639
Number of pages11
JournalJournal of Organometallic Chemistry
Volume690
Issue number3
DOIs
Publication statusPublished - Jan 28 2005

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Keywords

  • 1,4,7-Trithiacyclononane
  • Iridium complexes
  • Macrocyclic ligands
  • Mixed sandwich complexes
  • Pentamethylcyclopentadienide complexes
  • Rhodium complexes

ASJC Scopus subject areas

  • Chemical Engineering (miscellaneous)
  • Materials Science (miscellaneous)
  • Materials Chemistry
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry
  • Biochemistry

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