Electronic Structure of Cycloheptatrienyl Sandwich Compounds of Actinides: An(7-C7H7)2 (An
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- 作者：Jun Li and Bruce E. Bursten
- 刊名：Journal of the American Chemical Society
- 出版年：1997
- 出版时间：September 24, 1997
- 年：1997
- 卷：119
- 期：38
- 页码：9021 - 9032
- 全文大小：303K
- 年卷期：v.119,no.38(September 24, 1997)
- ISSN：1520-5126
文摘
The cycloheptatrienyl actinide sandwich compoundsAn(
7-C7H7)2q(An = Th-Am; q = 2-, 1-, 0, 1+)have been studied by using local and gradient-corrected densityfunctional methods, with the inclusion of scalar(mass-velocity and Darwin) relativistic effects. It has beenfound that the staggered conformer ofU(7-C7H7)2-ismore stable than the eclipsed one by about 0.6 kcal/mol. The f
orbitals not only participate in the bonding with thee2'' p
orbitals of the C7H7rings, but are as important as the d orbitals in stabilizing thefrontier p orbitals of theC7H7 rings. With increasing atomic numberof the actinide, the 5f manifold and ligand based frontier MOsbecomeconsiderably closer in energy. As a result, the actinide 5fpercentage in the frontier e2'' MOs increasesmarkedly,while the contribution by the 6d orbitals gradually decreases. Theground electron configurations, ionization energies,electron affinities, and An-C7H7 bondenergies are strongly affected by these effects. The bondinganalysis indicatesthatU(7-C7H7)2-and U(7-C7H7)2 arebest considered as complexes of U(III) and U(IV),respectively.
7-C7H7)2q(An = Th-Am; q = 2-, 1-, 0, 1+)have been studied by using local and gradient-corrected densityfunctional methods, with the inclusion of scalar(mass-velocity and Darwin) relativistic effects. It has beenfound that the staggered conformer ofU(7-C7H7)2-ismore stable than the eclipsed one by about 0.6 kcal/mol. The forbitals not only participate in the bonding with thee2'' p orbitals of the C7H7rings, but are as important as the d orbitals in stabilizing thefrontier p orbitals of theC7H7 rings. With increasing atomic numberof the actinide, the 5f manifold and ligand based frontier MOsbecomeconsiderably closer in energy. As a result, the actinide 5fpercentage in the frontier e2'' MOs increasesmarkedly,while the contribution by the 6d orbitals gradually decreases. Theground electron configurations, ionization energies,electron affinities, and An-C7H7 bondenergies are strongly affected by these effects. The bondinganalysis indicatesthatU(7-C7H7)2-and U(7-C7H7)2 arebest considered as complexes of U(III) and U(IV),respectively.