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Titolo:
STRETCHED MOLECULAR-HYDROGEN COMPLEXES OF OSMIUM(II) - A QUANTUM-CHEMICAL STUDY OF THE INFLUENCE OF THE TRANS LIGAND ON GEOMETRIES, SPIN-SPIN COUPLING-CONSTANTS, BONDING, AND CHARGE-DISTRIBUTIONS
Autore:
CRAW JS; BACSKAY GB; HUSH NS;
Indirizzi:
UNIV SYDNEY,DEPT PHYS & THEORET CHEM SYDNEY NSW 2006 AUSTRALIA UNIV SYDNEY,DEPT PHYS & THEORET CHEM SYDNEY NSW 2006 AUSTRALIA UNIV SYDNEY,DEPT BIOCHEM SYDNEY NSW 2006 AUSTRALIA
Titolo Testata:
Journal of the American Chemical Society
fascicolo: 13, volume: 116, anno: 1994,
pagine: 5937 - 5948
SICI:
0002-7863(1994)116:13<5937:SMCOO->2.0.ZU;2-B
Fonte:
ISI
Lingua:
ENG
Soggetto:
CONFIGURATION INTERACTION CALCULATIONS; H-H BOND; OXIDATIVE ADDITION; METAL COMPLEXES; ELECTRONIC-STRUCTURE; ABINITIO MO; REDUCTIVE ELIMINATION; POPULATION ANALYSIS; OCCUPATION NUMBERS; SIGMA-BOND;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
82
Recensione:
Indirizzi per estratti:
Citazione:
J.S. Craw et al., "STRETCHED MOLECULAR-HYDROGEN COMPLEXES OF OSMIUM(II) - A QUANTUM-CHEMICAL STUDY OF THE INFLUENCE OF THE TRANS LIGAND ON GEOMETRIES, SPIN-SPIN COUPLING-CONSTANTS, BONDING, AND CHARGE-DISTRIBUTIONS", Journal of the American Chemical Society, 116(13), 1994, pp. 5937-5948

Abstract

A theoretical study of the stretched molecular hydrogen complexes [Os(NH3)(4)L(z)(eta(2)-H-2)]((z+2)+)(L(z) = (CH3)(2)-CO, H2O, CH3COO-, Cl-, H-, C5H5N, and CH3CN) is reported. Using SCF and MP2 methods in conjunction with effective core potentials and basis sets of triple-zeta quality on Os and double-zeta on the ligand atoms the geometries, HD spin-spin coupling constants, and binding energies have been calculatedand compared with the available experimental data. The calculated H-Hdistances are remarkably uniform: all fall in the range 1.30-1.40 Angstrom and correspond to stretched eta 2-H-2 complexes, i.e. no cis-dihydrides have been found. The predicted H-H distance in the acetate complex is consistent with the observed distance of 1.34 Angstrom in the ethylenediamine derivative. A unique feature of these complexes is thecrucial role that electron correlation has on the H-H bond lengths; this is a consequence of the unusual potential energy surfaces that areextraordinarily flat with respect to the H-H stretch. The calculated Os-H bond lengths and stretching frequencies are also consistent with experiment. The calculated HD spin-spin coupling constants (J(HD)) areof the same order of magnitude as those observed, yet the trend in the latter with changing trans ligand L(z) is not adequately reproduced by the calculations, although a reasonable correlation between experimental J(HD) and calculated H-H distance is demonstrated. In order to elucidate the nature of the Os-H-2 bonding, population analyses as wellas an analysis of the binding energy of the Cl- complex have been carried out and these further emphasize the importance of electron correlation. At the simplest level, the effect of the trans ligand L(z) on the properties of the complexes can be related to its spectrochemical constant, which correlates with H-H distance and binding energy as wellas HD spin-spin coupling constant.

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Documento generato il 24/11/20 alle ore 22:22:15