Halogen Bonding Involving I<sub>2</sub> and d<sup>8</sup> Transition-Metal Pincer Complexes
We systematically investigated iodine–metal and iodine–iodine bonding in van Koten’s pincer complex and 19 modifications changing substituents and/or the transition metal with a PBE0–D3(BJ)/aug–cc–pVTZ/PP(M,I) model chemistry. As a novel tool for the quantitative assessment of the iodine–metal and i...
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MDPI AG
2021-04-01
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| Online Access: | https://www.mdpi.com/2073-4352/11/4/373 |
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| author | Marek Freindorf Seth Yannacone Vytor Oliveira Niraj Verma Elfi Kraka |
| author_facet | Marek Freindorf Seth Yannacone Vytor Oliveira Niraj Verma Elfi Kraka |
| author_sort | Marek Freindorf |
| collection | DOAJ |
| description | We systematically investigated iodine–metal and iodine–iodine bonding in van Koten’s pincer complex and 19 modifications changing substituents and/or the transition metal with a PBE0–D3(BJ)/aug–cc–pVTZ/PP(M,I) model chemistry. As a novel tool for the quantitative assessment of the iodine–metal and iodine–iodine bond strength in these complexes we used the local mode analysis, originally introduced by Konkoli and Cremer, complemented with NBO and Bader’s QTAIM analyses. Our study reveals the major electronic effects in the catalytic activity of the M–I–I non-classical three-center bond of the pincer complex, which is involved in the oxidative addition of molecular iodine I<sub>2</sub> to the metal center. According to our investigations the charge transfer from the metal to the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>σ</mi><mo>*</mo></msup></semantics></math></inline-formula> antibonding orbital of the I–I bond changes the 3c–4e character of the M–I–I three-center bond, which leads to weakening of the iodine I–I bond and strengthening of the metal–iodine M–I bond, facilitating in this way the oxidative addition of I<sub>2</sub> to the metal. The charge transfer can be systematically modified by substitution at different places of the pincer complex and by different transition metals, changing the strength of both the M–I and the I<sub>2</sub> bonds. We also modeled for the original pincer complex how solvents with different polarity influence the 3c–4e character of the M–I–I bond. Our results provide new guidelines for the design of pincer complexes with specific iodine–metal bond strengths and introduce the local vibrational mode analysis as an efficient tool to assess the bond strength in complexes. |
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| language | English |
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| publishDate | 2021-04-01 |
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| series | Crystals |
| spelling | doaj.art-f837e960a8944899a61ab73db1f26af32023-11-21T14:08:39ZengMDPI AGCrystals2073-43522021-04-0111437310.3390/cryst11040373Halogen Bonding Involving I<sub>2</sub> and d<sup>8</sup> Transition-Metal Pincer ComplexesMarek Freindorf0Seth Yannacone1Vytor Oliveira2Niraj Verma3Elfi Kraka4Department of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275-0314, USADepartment of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275-0314, USADepartamento de Quimica, Instituto Tecnologico de Aeronautica (ITA), Sao Jose dos Campos, Sao Paulo, SP 12228-900, BrazilDepartment of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275-0314, USADepartment of Chemistry, Southern Methodist University, 3215 Daniel Avenue, Dallas, TX 75275-0314, USAWe systematically investigated iodine–metal and iodine–iodine bonding in van Koten’s pincer complex and 19 modifications changing substituents and/or the transition metal with a PBE0–D3(BJ)/aug–cc–pVTZ/PP(M,I) model chemistry. As a novel tool for the quantitative assessment of the iodine–metal and iodine–iodine bond strength in these complexes we used the local mode analysis, originally introduced by Konkoli and Cremer, complemented with NBO and Bader’s QTAIM analyses. Our study reveals the major electronic effects in the catalytic activity of the M–I–I non-classical three-center bond of the pincer complex, which is involved in the oxidative addition of molecular iodine I<sub>2</sub> to the metal center. According to our investigations the charge transfer from the metal to the <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msup><mi>σ</mi><mo>*</mo></msup></semantics></math></inline-formula> antibonding orbital of the I–I bond changes the 3c–4e character of the M–I–I three-center bond, which leads to weakening of the iodine I–I bond and strengthening of the metal–iodine M–I bond, facilitating in this way the oxidative addition of I<sub>2</sub> to the metal. The charge transfer can be systematically modified by substitution at different places of the pincer complex and by different transition metals, changing the strength of both the M–I and the I<sub>2</sub> bonds. We also modeled for the original pincer complex how solvents with different polarity influence the 3c–4e character of the M–I–I bond. Our results provide new guidelines for the design of pincer complexes with specific iodine–metal bond strengths and introduce the local vibrational mode analysis as an efficient tool to assess the bond strength in complexes.https://www.mdpi.com/2073-4352/11/4/373density functional theoryhypervalent iodinelocal vibrational mode theoryvibrational spectroscopypincer complexes |
| spellingShingle | Marek Freindorf Seth Yannacone Vytor Oliveira Niraj Verma Elfi Kraka Halogen Bonding Involving I<sub>2</sub> and d<sup>8</sup> Transition-Metal Pincer Complexes Crystals density functional theory hypervalent iodine local vibrational mode theory vibrational spectroscopy pincer complexes |
| title | Halogen Bonding Involving I<sub>2</sub> and d<sup>8</sup> Transition-Metal Pincer Complexes |
| title_full | Halogen Bonding Involving I<sub>2</sub> and d<sup>8</sup> Transition-Metal Pincer Complexes |
| title_fullStr | Halogen Bonding Involving I<sub>2</sub> and d<sup>8</sup> Transition-Metal Pincer Complexes |
| title_full_unstemmed | Halogen Bonding Involving I<sub>2</sub> and d<sup>8</sup> Transition-Metal Pincer Complexes |
| title_short | Halogen Bonding Involving I<sub>2</sub> and d<sup>8</sup> Transition-Metal Pincer Complexes |
| title_sort | halogen bonding involving i sub 2 sub and d sup 8 sup transition metal pincer complexes |
| topic | density functional theory hypervalent iodine local vibrational mode theory vibrational spectroscopy pincer complexes |
| url | https://www.mdpi.com/2073-4352/11/4/373 |
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