Investigation of the Dithiolene Ligand Conformation in Analogous U(IV)/U(V) Complexes: X-ray Diffraction and Density Functional Theory Analysis of the U···(C=C) Interaction
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- 作者：Lotfi Belkhiri ; Thé ; rè ; se Arliguie ; Pierre Thué ; ry ; Marc Fourmigué ; Abdou Boucekkine ; and Michel Ephritikhine
- 刊名：Organometallics
- 出版年：2006
- 出版时间：May 22, 2006
- 年：2006
- 卷：25
- 期：11
- 页码：2782 - 2795
- 全文大小：6099K
- 年卷期：v.25,no.11(May 22, 2006)
- ISSN：1520-6041
文摘
Elucidation of the crystal structure of the dianionic complex [Na(18-crown-6)(thf)2]2[U(COT)(dddt)2](COT = 
8-C8H8, dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate), complementing that of [Na(18-crown-6)(thf)][U(COT)(dddt)2], allowed the first structural comparison of analogous uranium(IV) and -(V)compounds with anionic sulfur ligands. The distinct conformations of the dithiolene ligands, exo-exoand exo-endo in the uranium (IV) and -(V) complexes, respectively, are the observable manifestation ofthe differences in the metal-ligand bonding according to the oxidation state of the metal. The relationshipbetween electronic structure, bonding, and conformational changes in these dianionic uranium(IV) andanionic uranium(V) species and the hypothetical neutral uranium(VI) counterpart has been investigatedin the framework of relativistic density functional theory. The calculations reveal the occurrence in theuranium(V) anionic species of a significant intramolecular interaction involving the 5f metal orbitals andthe C=C double bond of the endo dithiolene ligand, which stabilizes its peculiar exo-endo conformation.Such an interaction does not exist in the uranium(IV) complex.
8-C8H8, dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate), complementing that of [Na(18-crown-6)(thf)][U(COT)(dddt)2], allowed the first structural comparison of analogous uranium(IV) and -(V)compounds with anionic sulfur ligands. The distinct conformations of the dithiolene ligands, exo-exoand exo-endo in the uranium (IV) and -(V) complexes, respectively, are the observable manifestation ofthe differences in the metal-ligand bonding according to the oxidation state of the metal. The relationshipbetween electronic structure, bonding, and conformational changes in these dianionic uranium(IV) andanionic uranium(V) species and the hypothetical neutral uranium(VI) counterpart has been investigatedin the framework of relativistic density functional theory. The calculations reveal the occurrence in theuranium(V) anionic species of a significant intramolecular interaction involving the 5f metal orbitals andthe C=C double bond of the endo dithiolene ligand, which stabilizes its peculiar exo-endo conformation.Such an interaction does not exist in the uranium(IV) complex.