Publications [#233771] of Richard A. Palmer
Journal Articles
- Meredith, PL; Palmer, RA, "Polarized Crystal Spectra of Bis(DL-histidinato)nickel(II) monohydrate and Bis(L-histidinato)nickel(II) monohydrate", Inorg. Chem., 1971, 10(5), 1049, American Chemical Society (ACS) [doi].
(last updated on 2024/07/16)Abstract:
The polarized single-crystal electronic spectra of Ni(DL-his)2·H2O (specifically the racemic lattice compound Ni(D-his)2Ni(L-his)2·2H2O) and of Ni(L-his)2·H2O have been obtained at ambient and cryogenic temperatures (his = histidinate). For the orthorhombic crystal of the racemate, the molecular polarizations have been calculated from the spectra measured with the electric vector of the radiation parallel to the crystallographic axes. The correction for the 11° misalignment of the molecular axes with respect to the extinction directions is seen to be minimal. The spectra of the monoclinic levo crystal show only moderate intensity variations from those of the racemic crystal. Comparison of the crystal spectra to that of the aqueous solution supports the assumption of the oriented gas model. Using the spectra of the racemic crystal as a guide, the molecular spectra have been interpreted in terms of the triaxial point group C2v. Intensity not conforming to the pure electric dipole selection rules has been shown to be very temperature dependent. Allowing vibrations have been assigned for these vibronic transitions. The observed maxima have been compared by least-squares analysis to the eigenvalues calculated in a ligand field model in which the potential is expanded in terms of tesseral harmonics. Fitting the spectra as assigned using the C2v selection rules gives a Dq of — 1125 cm-1 while B and C are found to be 783 and 3653 cm-1, respectively. In the analysis nine experimentally observed bands have been fit to ± 100 cm-1. © 1971, American Chemical Society. All rights reserved.