Electron paramagnetic resonance spectra of copper (II) and oxovanadium (IV) complexes oriented in nematic glasses from liquid crystal solvent

Abstract

The electron paramagnetic resonance (epr) spectra of a series of copper(I1) and oxovanadium(1V) complexes oriented in nematic glasses formed from liquid crystals have been measured. Data are presented which show that anisotropic epr parameters obtained by this convenient, easily interpreted technique compare favorably with published values obtained by dilute single crystal procedures. The results are substantially better than data obtained from randomly oriented frozen solutions or powders. The applicability of available theories concerned with the order present in liquid crystal solutions is discussed as it relates to the precision of the epr parameters. As an illustration of the usefulness of the technique, epr parameters are obtained for ten copper(I1) and seven oxovanadium-(IV) metal-organic complexes. Molecular orbital coefficients are calculated for the copper(I1) species.ingle-crystal electron paramagnetic resonance (epr)(1) Abstracted in part from the thesis of J. D. L. submitted in partial fulfillment for the Ph.D. degree in 1970 at Case Western Reserve University.(2) (a) B. R. McGarvey, Transition Metal Chem., 3, 89 (1966), and references cited therein; (b) M. J. Weeks and J. P. Fackler, Inorg.

Quantum coherence in a processable vanadyl complex: new tools for the search of molecular spin qubits

“…Spectral simulations were performed 42 on the basis of the following spin Hamiltonian: ℋ = Î ·A· ŝ + μ B ŝ · g · B providing as best-fit parameters: g x = 1.9880(2); g y = 1.9815(3); g z = 1.9490(2) and A x = 0.0056(1) cm –1 (167.9 MHz); A y = 0.0063(3) cm –1 (190.4 MHz); A z = 0.0170(2) cm –1 (509.6 MHz). These parameters are in the range previously reported for VO 2+ β-diketonate-type derivatives 43 , 44 and are consistent with the slight structural rhombicity observed by X-ray diffractometry. These spin Hamiltonian parameters have been employed to draw the Zeeman diagrams reported in Fig.…”

Giant spin–phonon bottleneck effects in evaporable vanadyl-based molecules with long spin coherence

“…The spectra have been simulated 34 on the basis of the Spin Hamiltonian H = μ B B•g•S + I•A•S, providing almost identical parameters for the three derivatives (Table S1 †) indicating only negligible differences in the electronic structure of the complexes. The obtained parameters are in the range previously reported for VO 2+ β-diketonate-type derivatives 35,36 and are characterized, as expected, by partially rhombic g and A tensors. Larger deviations from the free electron values for g and larger hyperfine coupling are observed along the z direction, which is directed along the VvO bond.…”

Forty-Five Years of Chemical Discovery Including a Golden Quarter-Century

“…A liquid crystal technique we developed later was applied by Hoffman to studies of inorganic and biological materials. This work showed that the EPR of “flat” molecular metal β-ketoenolates could be used to determine spin-polarization directions in frozen liquid crystals . In our Jahn−Teller studies, we were fortunate to recognize that the previously reported, nearly octahedral structure of the MnO 6 bonding in Mn(acac) 3 was incompatible with its visible spectrum and successfully showed that the molecule actually is tetragonally distorted.…”