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Singh A, Avinash K, Malaspina LA, Banoo M, Alhameedi K, Jayatilaka D, Grabowsky S, Thomas SP. Dynamic Covalent Bonds in the Ebselen Class of Antioxidants Probed by X-ray Quantum Crystallography. Chemistry 2024; 30:e202303384. [PMID: 38126954 DOI: 10.1002/chem.202303384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Revised: 12/19/2023] [Accepted: 12/20/2023] [Indexed: 12/23/2023]
Abstract
Dynamic bonds are essential structural ingredients of dynamic covalent chemistry that involve reversible cleavage and formation of bonds. Herein, we explore the electronic characteristics of Se-N bonds in the organo-selenium antioxidant ebselen and its derivatives for their propensity to function as dynamic covalent bonds by employing high-resolution X-ray quantum crystallography and complementary computational studies. An analysis of the experimentally reconstructed X-ray wavefunctions reveals the salient electronic features of the Se-N bonds with very low electron density localized at the bonding region and a positive Laplacian value at the bond critical point. Bond orders and percentage covalency and ionicity estimated from the X-ray wavefunctions, along with localized orbital locator (LOL) and electron localization function (ELF) analyses show that the Se-N bond is unique in its closed shell-like features, despite being a covalent bond. Time-dependent DFT calculations simulate the cleavage of Se-N bonds in ebselen in the excited state, further substantiating their nature as dynamic bonds.
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Affiliation(s)
- Ashi Singh
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Kiran Avinash
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Lorraine A Malaspina
- University of Bern, Department of Chemistry, Biochemistry and Pharmaceutical Sciences, Freiestrasse 3, 3012, Bern, Switzerland
| | - Masoumeh Banoo
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Khidhir Alhameedi
- School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia
- Faculty of Education for Pure Sciences -, University of Kerbala, Karbala, Iraq
| | - Dylan Jayatilaka
- School of Molecular Sciences, University of Western Australia, Perth, WA, 6009, Australia
| | - Simon Grabowsky
- University of Bern, Department of Chemistry, Biochemistry and Pharmaceutical Sciences, Freiestrasse 3, 3012, Bern, Switzerland
| | - Sajesh P Thomas
- Department of Chemistry, Indian Institute of Technology Delhi, New Delhi, 110016, India
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