Structural, spectroscopic and redox characterization of the soluble complexes [M(SC6H4NR2)4]2- and the effects of N-H ... S hydrogen bonds

Jiong Huang, John C. Dewan, M. Anton Walters

Research output: Contribution to journalArticle

Abstract

The complex [(C2H5)4N]Na[Fe(SC6H4NH2-2)4] (1) has been synthesized in order to study the influence of ligand hydrogen bonding on the redox potential of monomeric iron-sulfur complexes. Compound 1 crystallizes in space group P 21 c, with a = 11.747(4), b = 25.058(5), c = 12.301(3) A ̊, β = 106.22(2)° and Z = 4. The related cobalt complex [(C2H5)4N]2[Co(SC6H4NH2-2)4] (2) was also synthesized and found to crystallize in space group Pccn with a = 12.544(3), b = 13.920(3), c = 24.646(15) A ̊and Z = 4. The average MS bond length is 2.341(1) Å in 1 and 2.295(2) Å in 2. The electronic absorption spectrum of 2 is consistent with an equilibrium between the respective tetrahedral and pseudo-octahedral complexes [Co(SC6H4NH2-2)4]2- and [Co(SC6H4NH2-2)3]-. The proton NMR spectra of 1 and 2 in saturated CD3CN solutions show unusually broad, isotropically shifted ligand proton signals, indicative of exchange broadening. This result is consistent with the occurrence of [M(SC6H4NH2-2)4]2- complex anions in equilibrium with species that could not be identified by 1H NMR. The cyclic voltammetry data for 1, 12.0 mM in CH3CN, show two irreversible redox waves with Eox at -0.50 and -0.25 V, respectively, relative to SCE. The peak at -0.50 V is a likely candidate for the redox couple of the complex [Fe(SC6H4NH2-2)4]2-. The peak at -0.25 V probably belongs to a pseudo-octahedral iron complex.

Original languageEnglish (US)
Pages (from-to)199-206
Number of pages8
JournalInorganica Chimica Acta
Volume228
Issue number2
DOIs
StatePublished - Jan 15 1995

Keywords

  • Cobalt complexes
  • Crystal structures
  • Electrochemistry
  • Iron complexes
  • Thiolate complexes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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