Structural study of bromo-bridged 3Ne-dimensional Niii-Niivmixed valence complexes by means of exafs

K. Toriumi, T. Kanao, Y. Umetsu, A. Ohyoshi, M. Yamashita, T. Ito

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6 Citations (Scopus)

Abstract

Nickel K-edge and Bromine K-edge EXAFS spectra have been measured for Br-bridged one-dimensional NiII-NiIVmixed valence compounds and their reference NiIIand NiIIIcomplexes. Fourier transforms of the Br K- and Ni K-edge EXAFS data of the mixed valence compounds show one and two sharp peaks, respectively, assigned to the Br-Ni distance, and the Ni-N and Ni-Br distances. By applying least-squares curve-fitting analyses for the Fourier back-transformed first peaks, a mean NiIV-Br distance for the mixed valence compounds has been determined to be 2.64 A, which is comparable to 2.63 A for the discrete NiIIIcomplex. This suggests a significant elongation of the NiIV-Br bond owing to the charge transfer interaction between the NiIIand NiIVatoms, resulting in the high electrical conductivities of NiII-NiIVcompounds as compared with those of the Pd and Pt analogues. Mean Ni-N distances were accurately determined and were found to increase in the order, octahedral high-spin NiII> octahedral NiIII≃ octahedral NiIV, and square-planar NiIIin the mixed valence compound ≥ square-planar low-spin NiIIin the discrete complex. The NiII… Br distance in the mixed valence compound could not be obtained, possibly Awing to the essentially weak bonding nature.

Original languageEnglish
Pages (from-to)209-221
Number of pages13
JournalJournal of Coordination Chemistry
Volume19
Issue number1-3
DOIs
Publication statusPublished - 1988 Dec 1
Externally publishedYes

Keywords

  • EXAFS
  • complexes
  • conductivity
  • nickel(II, IV)
  • one-dimensional compound

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Chemistry

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