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Bis(α-diimine)iron Complexes: Electronic Structure Determination by Spectroscopy and Broken Symmetry Density Functional Theoretical Calculations

Muresan, Nicoleta and Lu, Connie C. and Ghosh, Meenakshi and Peters, Jonas C. and Abe, Megumi and Henling, Lawrence M. and Weyhermöller, Thomas and Bill, Eckhard and Wieghardt, Karl (2008) Bis(α-diimine)iron Complexes: Electronic Structure Determination by Spectroscopy and Broken Symmetry Density Functional Theoretical Calculations. Inorganic Chemistry, 47 (11). pp. 4579-4590. ISSN 0020-1669. https://resolver.caltech.edu/CaltechAUTHORS:20140805-072235251

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Abstract

The electronic structure of a family comprising tetrahedral (α-diimine)iron dichloride, and tetrahedral bis(α-diimine)iron compounds has been investigated by Mössbauer spectroscopy, magnetic susceptibility measurements, and X-ray crystallography. In addition, broken-symmetry density functional theoretical (B3LYP) calculations have been performed. A detailed understanding of the electronic structure of these complexes has been obtained. A paramagnetic (S_t = 2), tetrahedral complex [Fe^(II)(^4L)_2], where (^4L)^(1−) represents the diamagnetic monoanion N-tert-butylquinolinylamide, has been synthesized and characterized to serve as a benchmark for a Werner-type complex containing a tetrahedral Fe^(II)N_4 geometry and a single high-spin ferrous ion. In contrast to the most commonly used description of the electronic structure of bis(α-diimine)iron(0) complexes as low-valent iron(0) species with two neutral α-diimine ligands, it is established here that they are, in fact, complexes containing two (α-diiminato)^(1−•) π radical monoanions and a high-spin ferrous ion (in tetrahedral N_4 geometry) (S_(Fe) = 2). Intramolecular antiferromagnetic coupling between the π radical ligands (S_(rad) = 1/2) and the ferrous ion (S_(Fe) = 2) yields the observed S_t = 1 ground state. The study confirms that α-diimines are redox noninnocent ligands with an energetically low-lying antibonding π^* lowest unoccupied molecular orbital which can accept one or two electrons from a transition metal ion. The (α-diimine)FeCl_2 complexes (St = 2) are shown to contain a neutral α-diimine ligand, a high spin ferrous ion, and two chloride ligands.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://pubs.acs.org/doi/abs/10.1021/ic7022693PublisherArticle
http://dx.doi.org/10.1021/ic7022693DOIArticle
http://pubs.acs.org/doi/suppl/10.1021/ic7022693Related ItemSupporting Information
ORCID:
AuthorORCID
Peters, Jonas C.0000-0002-6610-4414
Additional Information:© 2008 American Chemical Society. Received November 19, 2007. Publication Date (Web): April 29, 2008. N.M. and M.G. are grateful to the Max-Planck Society for a postdoctoral stipend and C.C.L. thanks the A. v. Humboldt Foundation for a fellowship. We gratefully acknowledge financial support from the Fonds of the Chemical Industry. M.A. thanks the Caltech SURF program for funding. We also would like to thank Dr. K. Chlopek for preliminary DFT calculations of 8.
Funders:
Funding AgencyGrant Number
Max-Planck SocietyUNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Fonds of the Chemical IndustryUNSPECIFIED
Caltech SURF programUNSPECIFIED
Issue or Number:11
Record Number:CaltechAUTHORS:20140805-072235251
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140805-072235251
Official Citation:Bis(α-diimine)iron Complexes: Electronic Structure Determination by Spectroscopy and Broken Symmetry Density Functional Theoretical Calculations Nicoleta Muresan, Connie C. Lu, Meenakshi Ghosh, Jonas C. Peters, Megumi Abe, Lawrence M. Henling, Thomas Weyhermöller, Eckhard Bill, and Karl Wieghardt Inorganic Chemistry 2008 47 (11), 4579-4590
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47956
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:05 Aug 2014 16:08
Last Modified:26 Nov 2019 11:15

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