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)
- 7 May 2002
- journal article
- research article
- Published by American Chemical Society (ACS) in Inorganic Chemistry
- Vol. 41 (11) , 2826-2833
- https://doi.org/10.1021/ic011283e
Abstract
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 spin-Hamiltonian parameters gXX = 2.074, gYY = 2.093, gZZ = 2.385, DXX = ±0.0228 cm-1, DYY = ±0.0211 cm-1, DZZ = ∓0.0439 cm-1 with Euler angles of α = 179°, χ = 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.Keywords
This publication has 28 references indexed in Scilit:
- Single-crystal and multi-frequency EPR studies on chemical analogues of Amavadin: V(IV)-doped Ca[Ti(hida)2]·6H2O, and Mo(V)-doped [PPh4][Nb(hida)2] and [NEt4][Ta(R,R-hidpa)2] [H3hida=2,2′-(hydroxyimino)diacetic acid, H3hidpa=2,2′-(hydroxyimino)dipropionic acid]Journal of the Chemical Society, Faraday Transactions, 1998
- Single-crystal electron paramagnetic resonance of (dialkyldithiocarbamato-S,S′)[hydrotris(3,5-dimethylpyrazolyl)borato] oxovanadium(IV)(alkyl = ethyl or n-propyl)Journal of the Chemical Society, Faraday Transactions, 1993
- The single-crystal electron spin resonance spectra of bis chloro bis(N,N′-substituted urea)oxovanadium(IV) compounds diluted in the corresponding tris-chloro bis(N,N′-substituted)urea indium(III) compoundsSpectrochimica Acta Part A: Molecular Spectroscopy, 1991
- Crystal and molecular structure of bis(tetraphenylphosphonium) bis(1,2-dicyanoethylene-1,2-dithiolato)oxovanadate(IV). Its single-crystal electron spin resonance as a pure compound and diluted in the isomorphous molybdenum(IV) compoundJ. Chem. Soc., Dalton Trans., 1988
- The first mononuclear molybdenum(V) complex with a terminal sulfido ligand: dichloro[hydrotris(3,5-dimethyl-1-pyrazolyl)borato]sulfidomolybdenumInorganic Chemistry, 1987
- The single-crystal electron spin resonance spectrum of oxobis(2-methylquinolin-8-olato)vanadium(IV) as a pure compound and diluted in chlorobis(2-methylquinolin-8-olato)gallium(III)J. Chem. Soc., Dalton Trans., 1987
- Formation, crystal structure, and EPR spectroscopic properties of a heteronuclear (Pt2,Cu) mixed-nucleobase (1-methylcytosine, 1-methyluracil) complex: bis[(.mu.-1-methyluracilato-N3,O4)(.mu.-1-methylcytosine-N3,O2)-cis-diammineplatinum(II)]copper(II) tetranitrate-6-waterInorganic Chemistry, 1984
- Single-crystal electron spin resonance spectra of tris(diethyldithiocarbamato)oxomolybdenum(V) and chlorobis(diethyldithiocarbamato)oxomolybdenum(V) diluted in isomorphous host latticesJ. Chem. Soc., Dalton Trans., 1981
- Electron spin resonance studies of some copper(II) peptide complexesJ. Chem. Soc. A, 1969
- Electron spin resonance studies of dimer formation by chelates of copper(II) with some amino-acidsJ. Chem. Soc. A, 1969