(NBu4)Ni(mnt)2: A novel bistable high temperature spin-Peierls-like system

Roger D. Willett, Carlos J. Gómez-García, B. L. Ramakrishna, Brendan Twamley

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Abstract

The title compound, tetrabutylammonium bis(1,2-dimercaptoethene-1,2- dicarbonirtilato-S,S′)-nickel (III) [henceforth (NBu4)Ni(mnt) 2] undergoes a hysteretic phase transition that occurs at 172 K upon cooling. Crystallographic studies show that the phase transition is an order-disorder type involving one arm of the NBu4+ cation. Both phases are monoclinic, space group C2/c with a = 30.860(3), b = 13.804(2), c = 15.678(2) Å and β = 115.642(3)° with V = 6020.8(11) Å3 at room temperature and with a = 31.073(3), b = 13.928(1), c = 14.414(1) Å and β = 115.073(2)° and V = 5652.1(9) Å3 at 84 K. In both phases, the anions form non-uniform stacks parallel to the crystallographic c direction. In the high temperature phase, the Ni-S distances between anions are accidentally equal, and the stacks behave as nearly uniform antiferromagnetic chains with nearly equal exchange constants. At the phase transition, a non-uniform compression of the stacks occurs and the magnetic moment drops rapidly, indicating a magnetic dimerization of the stacks. Susceptibility and Cp measurements show an approximate 7°C thermal hysteresis.

Original languageEnglish (US)
Pages (from-to)2232-2237
Number of pages6
JournalPolyhedron
Volume24
Issue number16-17
DOIs
StatePublished - Nov 17 2005

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Keywords

  • Antiferromagnetic chain
  • Bistable behavior
  • Crystal structure
  • Dimerization
  • Nickel dithiolate complex
  • Phase transition

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

Cite this

Willett, R. D., Gómez-García, C. J., Ramakrishna, B. L., & Twamley, B. (2005). (NBu4)Ni(mnt)2: A novel bistable high temperature spin-Peierls-like system. Polyhedron, 24(16-17), 2232-2237. https://doi.org/10.1016/j.poly.2005.03.088