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Detection and Measurement of Noncoincidence between the Principal Axes of the g-Matrix and Zero-Field Splitting Tensor Using Multifrequency Powder EPR Spectroscopy: Application to cis-[(NH3)2Pt(1-MeU)2Cu(H2O)2](SO4).4.5H2O (1-MeU = Monoanion of 1-Methyluracil)

journal contribution
posted on 2023-05-16, 13:49 authored by Collison, DC, Goodgame, DML, Hitchman, MA, Lippert, B, Mabbs, FE, McInnes, EJL
Multifrequency continuous wave EPR spectra (4-34 GHz) on a powder of the title compound are consistent with a spin-triplet state. This arises from interaction between centrosymmetrically related pairs of copper(II) ions in the solid. The spectra at all frequencies have been simulated with a single set of spin-Hamiltonian parameters. The results show that there is noncoincidence between the principal axes of the g-matrices on each copper center and those of the zero-field splitting (D) tensor. This noncoincidence is a single rotation of 33° ± 2°. The parameters from the powder spectra have been verified by a subsequent single-crystal EPR study which yielded the spinHamiltonian parameters g XX = 2.074, g YY = 2.093, g ZZ = 2.385, D XX = ±0.0228 cm -1, D YY = ±0.0211 cm -1, D ZZ = 0.0439 cm -1 with Euler angles of α = 179°, X = 33.4°, and γ = 328°. Analysis of the zero-field splitting tensor in terms of exchange indicates that the interaction between the pairs of copper(II) ions is almost entirely dipolar in origin. This study shows that multifrequency EPR spectroscopy on powders, coupled with spectrum simulation, can detect and measure noncoincidence between the principal axes of the g-matrix and zero-field splitting tensor, and does not necessarily require the presence of metal hyperfine interactions.

History

Publication title

Inorganic Chemistry

Volume

41

Issue

11

Pagination

2826-2833

ISSN

0020-1669

Department/School

School of Natural Sciences

Publisher

Amiercan Chemical Society

Place of publication

Washington, DC, USA

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the chemical sciences

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