Single-crystal electron paramagnetic resonance study of triplet excitons in [Fe(mesitylene)22+] [C3(C(CN) 2)3-]2

J. R. Morton, K. F. Preston, Y. Le Page, A. J. Williams, M. D. Ward

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Abstract

Single crystals of [Fe(mesitylene)22+] [C 3(C(CN)2)3-]2 exhibit an intense EPR spectrum with anisotropy and fine structure typical of an electronic triplet species (S=1). From measurements of the fine-structure splitting as a function of angle in three orthogonal crystal planes, it has been established that the spin-spin interaction tensor is nearly axial, D = (-218, 116, 105 MHz), and that the g tensor is almost isotropic with giso = 2.0027. The zero-field splitting parameters were determined as |D| = 327.8 MHz (117 G) and |E| = 5.7 MHz (2 G). Comparison of the principal directions of D with vectors within the known crystal structure shows that the triplet comprises a radical pair formed between nearest neighboring anions. The principal values and directions of D for the biradical compare well with those calculated for the unpaired spin density distribution deduced for the monoradical from its isotropic spectrum and from INDO calculations.

Original languageEnglish (US)
Pages (from-to)2222-2227
Number of pages6
JournalThe Journal of Chemical Physics
Volume93
Issue number4
DOIs
StatePublished - Jan 1 1990

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ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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