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Martins FA, de Azevedo Santos L, Rodrigues Silva D, Fonseca Guerra C, Bickelhaupt FM, Freitas MP. Iodine Gauche Effect Induced by an Intramolecular Hydrogen Bond. J Org Chem 2022; 87:11625-11633. [PMID: 35984736 DOI: 10.1021/acs.joc.2c01258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The gauche conformer in 1-X,2-Y-disubstituted ethanes, that is, the staggered orientation in which X and Y are in closer contact, is only favored for relatively small substituents that do not give rise to large X···Y steric repulsion. For more diffuse substituents, weakly attractive orbital interactions between antiperiplanar bonds (i.e., hyperconjugation) cannot overrule the repulsive forces between X and Y. Our quantum chemical analyses of the rotational isomerism of XCH2CH2Y (X = F, OH; Y = I) at ZORA-BP86-D3(BJ)/QZ4P reveal that indeed the anti conformer is generally favored due to a less destabilizing I···F and I···O-H steric repulsion. The only case when the gauche conformer is preferred is when the hydroxyl hydrogen is oriented toward the iodine atom in the 2-iodoethanol. This is because of the significantly stabilizing covalent component of the I···H-O intramolecular hydrogen bond. Therefore, we show that strong intramolecular interactions can overcome the steric repulsion between bulky substituents in 1,2-disubstituted ethanes and cause the gauche effect. Our quantum chemical computations have guided nuclear magnetic resonance experiments that confirm the increase in the gauche population as X goes from F to OH.
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Affiliation(s)
- Francisco A Martins
- Department of Chemistry, Institute of Natural Sciences, Federal University of Lavras, 37200-900 Lavras, Minas Gerais, Brazil
| | - Lucas de Azevedo Santos
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Daniela Rodrigues Silva
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Célia Fonseca Guerra
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Matheus P Freitas
- Department of Chemistry, Institute of Natural Sciences, Federal University of Lavras, 37200-900 Lavras, Minas Gerais, Brazil
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Dairo TO, Ellern A, Angelici RJ, Woo LK. Addition of Amines to a Carbonyl Ligand: Syntheses, Characterization, and Reactivities of Iridium(III) Porphyrin Carbamoyl Complexes. Organometallics 2014. [DOI: 10.1021/om500189a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Taiwo O. Dairo
- Department
of Chemistry, Iowa State University, Ames, Iowa 50011-3111, United States
| | - Arkady Ellern
- Department
of Chemistry, Iowa State University, Ames, Iowa 50011-3111, United States
| | - Robert J. Angelici
- Department
of Chemistry, Iowa State University, Ames, Iowa 50011-3111, United States
| | - L. Keith Woo
- Department
of Chemistry, Iowa State University, Ames, Iowa 50011-3111, United States
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