Molecules (Feb 2018)

Synthesis and Magnetic Properties of Stable Radical Derivatives Carrying a Phenylacetylene Unit

  • Shogo Miyashiro,
  • Tomoaki Ishii,
  • Youhei Miura,
  • Naoki Yoshioka

DOI
https://doi.org/10.3390/molecules23020371
Journal volume & issue
Vol. 23, no. 2
p. 371

Abstract

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A nitronyl nitroxide derivative, 2-phenylethynyl-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl-3-oxide (1), and two verdazyl derivatives carrying a phenylacetylene unit, 1,5-diphenyl-3-phenylethynyl-6-oxo-1,2,4,5-tetrazin-2-yl (2) and 1,5-diisopropyl-3-phenylethynyl-6-oxo-1,2,4,5-tetrazin-2-yl (3), were synthesized and their packing structures were studied by X-ray crystallographic analysis and magnetically characterized in the solid state. While 1 and 3 had an isolated doublet spin state, 2 formed an antiferromagnetically coupled pair (2J/kB = −118 K). Density functional theory (DFT) calculations reveal that the spin density polarized in the phenyl group decreases as the dihedral angle between the phenyl ring and radical plane increases.

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