Geometric and electronic structure of a peroxomanganese(III) complex supported by a scorpionate ligand
| Autor: | Robert A. Geiger, Gayan B. Wijeratne, Victor W. Day, Timothy A. Jackson, Hannah E. Colmer, Domenick F. Leto |
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| Rok vydání: | 2014 |
| Předmět: |
Circular dichroism
Manganese Absorption spectroscopy Magnetic circular dichroism Chemistry Circular Dichroism Electron Spin Resonance Spectroscopy Molecular Conformation Electronic structure Crystal structure Scorpionate ligand Photochemistry Crystallography X-Ray Ligands Article Inorganic Chemistry Bond length Crystallography X-Ray Absorption Spectroscopy Coordination Complexes Density functional theory |
| Zdroj: | Dalton transactions (Cambridge, England : 2003). 43(48) |
| ISSN: | 1477-9234 |
| Popis: | A monomeric Mn(II) complex has been prepared with the facially-coordinating Tp(Ph2) ligand, (Tp(Ph2) = hydrotris(3,5-diphenylpyrazol-1-yl)borate). The X-ray crystal structure shows three coordinating solvent molecules resulting in a six-coordinate complex with Mn-ligand bond lengths that are consistent with a high-spin Mn(II) ion. Treatment of this Mn(II) complex with excess KO2 at room temperature resulted in the formation of a Mn(III)-O2 complex that is stable for several days at ambient conditions, allowing for the determination of the X-ray crystal structure of this intermediate. The electronic structure of this peroxomanganese(III) adduct was examined by using electronic absorption, electron paramagnetic resonance (EPR), low-temperature magnetic circular dichroism (MCD), and variable-temperature variable-field (VTVH) MCD spectroscopies. Density functional theory (DFT), time-dependent (TD)-DFT, and multireference ab initio CASSCF/NEVPT2 calculations were used to assign the electronic transitions and further investigate the electronic structure of the peroxomanganese(III) species. The lowest ligand-field transition in the electronic absorption spectrum of the Mn(III)-O2 complex exhibits a blue shift in energy compared to other previously characterized peroxomanganese(III) complexes that results from a large axial bond elongation, reducing the metal-ligand covalency and stabilizing the σ-antibonding Mn dz(2) MO that is the donor MO for this transition. |
| Databáze: | OpenAIRE |
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