Schnoeckelborg, Eva-Maria and Khusniyarov, Marat M. and de Bruin, Bas and Hartl, Frantisek and Langer, Thorsten and Eul, Matthias and Schulz, Stephen and Poettgen, Rainer and Wolf, Robert (2012) Unraveling the Electronic Structures of Low-Valent Naphthalene and Anthracene Iron Complexes: X-ray, Spectroscopic, and Density Functional Theory Studies. INORGANIC CHEMISTRY, 51 (12). pp. 6719-6730. ISSN 0020-1669, 1520-510X
Full text not available from this repository. (Request a copy)Abstract
Naphthalene and anthracene transition metalates are potent reagents, but their electronic structures have remained poorly explored. A study of four Cp*-substituted iron complexes (Cp* = pentamethylcyclopentadienyl) now gives rare insight into the bonding features of such species. The highly oxygen- and water-sensitive compounds [K(18-crown-6){Cp*Fe(eta(4)-C10H8)}] (K1), [K(18-crown-6)[Cp*Fe(eta(4)-C14H10)}] (K2), [Cp*Fe(eta(4)-C10H8)] (1), and [Cp*Fe(eta(4)-C14H10)] (2) were synthesized and characterized by NMR, UV-vis, and Fe-57 Mossbauer spectroscopy. The paramagnetic complexes 1 and 2 were additionally characterized by electron paramagnetic resonance (EPR) spectroscopy and magnetic susceptibility measurements. The molecular structures of complexes K1, K2, and 2 were determined by single-crystal X-ray crystallography. Cyclic voltammetry of 1 and 2 and spectroelectrochemical experiments revealed the redox properties of these complexes, which are reversibly reduced to the monoanions [Cp*Fe(eta(4)-C10H8)](-) (1(-)) and [Cp*Fe(eta(4)-C14H10)](-) (2(-)) and reversibly oxidized to the cations [Cp*Fe(eta(4)-C10H8)](+) (1(+)) and [Cp*Fe(eta(4)-C14H10](+) (2(+)). Reduced orbital charges and spin densities of the naphthalene complexes 1(-/0/+) and the anthracene derivatives 2(-/0/+) were obtained by density functional theory (DFT) methods. Analysis of these data suggests that the electronic structures of the anions 1(-) and 2(-) are best represented by low-spin Fe-II ions coordinated by anionic Cp* and dianionic naphthalene and anthracene ligands. The electronic structures of the neutral complexes 1 and 2 may be described by a superposition of two resonance configurations which, on the one hand, involve a low-spin Fe-I ion coordinated by the neutral naphthalene or anthracene ligand L, and, on the other hand, a low-spin Fe-II ion coordinated to a ligand radical L. Our study thus reveals the redox noninnocent character of the naphthalene and anthracene ligands, which effectively stabilize the iron atoms in a low formal, but significantly higher spectroscopic oxidation state.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | ORDER REGULAR APPROXIMATION; RICH TRANSITION-METALS; REACTIVE PI-COMPLEXES; TRIPLE ZETA VALENCE; GAUSSIAN-BASIS SETS; ISOCYANIDE COMPLEXES; CORRELATION-ENERGY; MOSSBAUER-SPECTRA; CRYSTAL-STRUCTURE; AB-INITIO; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Anorganische Chemie > Arbeitskreis Prof. Dr. Robert Wolf |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 11 May 2020 11:53 |
| Last Modified: | 11 May 2020 11:53 |
| URI: | https://pred.uni-regensburg.de/id/eprint/18574 |
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