Blacque, Oliver and Brunner, Henri and Kubicki, Marek M. and Leis, Franz and Lucas, Dominique and Mugnier, Yves and Nuber, Bernhard and Wachter, Joachim (2001) Structural rearrangements in triple-decker-like complexes with mixed group 15/16 ligands: Synthesis and characterization of the redox couple [Cp-2*Fe2As2Se2]/[Cp-2*Fe2As2Se2](+) (Cp*=C5Me5). CHEMISTRY-A EUROPEAN JOURNAL, 7 (6). pp. 1342-1349. ISSN 0947-6539
Full text not available from this repository.Abstract
The reaction of As4Se4 with stoichiometric amounts of [Cp-2*Fe-2(CO)(4)] (Cp* = C5Me5) in boiling toluene forms [Cp-2*Fe2As2Se2] (1) in good yield, X-ray crystallography shows 1 to have a triple-decker structure which comprises a tetraatomic mu,eta (4:4)-As2Se2 ligand. Density functional theory (DFT) and extended Huckel molecular orbital (EHMO) calculations confirm that the As2Se2 ligand behaves as a four-electron pi donor. Oxidation of 1 with equimolar amounts of [(C5H5)(2)Fe]PF6, Br-2 and I-2, respectively, gave compounds 2-4. According to X-ray crystallographic investigations that were carried out on 2 and 4, the oxidation state has a considerable influence on the structure of the Fe2As2Se2 core: significant shortening of the Fe-Fe distance (Deltad(Fe-Fe)> 0.3 Angstrom) and weakening of the As-As bond length ((Deltad(As-As) > 0.3 Angstrom) suggests the formal presence of two diatomic AsSe ligands and a Fe-Fe bond. DFT and EHMO calculations confirm that an electron is removed from an occupied Fe-Fe orbital of antibonding character during oxidation, All molecular orbitals lower their energies upon oxidation, but the energy drop is relatively small for those involving the As-As bond. An additional structural feature in 4 consists of an electronic interaction of the iodide with both As atoms which suggests a formally neutral ion pair. Electrochemical studies confirm that the oxidation of 1 is a reversible one-electron process with E-1/2 = +0.07 V (in THF). These studies also reveal that 4 dissociates in polar solvents, such as THF into [1](+) and I-, which is followed by transformation into 1 and I-3.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | TRANSITION-METAL-COMPLEXES; MAIN-GROUP; MOLECULAR-STRUCTURE; CRYSTAL-STRUCTURES; SANDWICH COMPLEX; CHEMISTRY; FRAGMENTATION; COORDINATION; CLUSTERS; AS2S3; arsenic; iron; selenium; structure elucidation |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Alumni or Retired Professors > Arbeitskreis Dr. Joachim Wachter Chemistry and Pharmacy > Institut für Anorganische Chemie > Alumni or Retired Professors > Prof. Dr. Henri Brunner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 08 Feb 2022 15:47 |
| Last Modified: | 08 Feb 2022 15:47 |
| URI: | https://pred.uni-regensburg.de/id/eprint/41637 |
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