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Spectroscopic Characterization, Crystal and Molecular Structure of [ReBr2N(PPh3)2]

Dzięgielewski J., Michalik S., Jaworska M., Kruszyński R., Kusz J.

Polish Journal of Chemistry

2005

Vol. 79 / nr 7

1193-1203

Rhenium nitrido-complex [ReNBr2(PPh3)2] has been characterized by X-ray diffraction, IR and UV-Vis spectroscopies. The geometry optimization was carried out with the DFT method using B3LYP functional. The electronic spectrum was calculated with the TDDFT method.

Molecular orbital estimation of reduced partition function ratios of lithium ions in ion exchanger phase of aqueous ion exchange systems

Yanase S., Oi T.

Nukleonika

2002

Vol. 47,suppl.1

75-79

Structures of Li+(H2O)5SO3 --R with -R representing the methyl and other groups modeling the lithium ion in the ion exchanger phase of aqueous ion exchange systems were optimized based on the molecular orbital theory and the reduced partition function ratios (RPFRs) for the 6Li/7Li isotope substitutions were estimated. The structure around the lithium ion was nearly unchanged by the substitutions of the methyl group by the other groups. Correspondingly, the RPFR value did not vary substantially, either; the maximum decrease of 0.0008 was observed for -R = -C(C2H5)3 from that of -CH3. It was indicated that the equilibrium constant of the lithium isotope exchange reaction between the ion exchanger and the external solution phases could change by ca. 0.001 without any substantial structural change around the lithium ion in the ion exchanger phase. It was also indicated the ONIOM calculation is effective when treating isotope effects of large molecules.

Theoretical studies on sulfur-containing radical ions

Carmichael I.

Nukleonika

2000

Vol. 45, nr 1

11-17

Structures and properties are reported for pi-radical cations and for sigma-radical cations and anions, containing SS, SN and SO odd-electron bonds, from a variety of ab initio molecular orbital techniques and Density Functional Theory (DFT). Characteristic frequencies and absorption bands are determined to aid in the assignment of transient vibrational and optical spectra detected in pulse radiolysis experiments. Hyperfine coupling tensors are evaluated to facilitate the identification of these radicals by EPR spectroscopy. By comparison with predictions from accurate coupled-cluster based calculations in some simple model systems, DFT is shown to have difficulties in correctly describing the electronic structure of these radical ions. Useful linear relationships are uncovered between the computed lenght of the odd-electron bond and both the wavelenght of maximum optical absorption and the bond stretching frequency.