Structure and Bonding Patterns in C<sub>5</sub>H<sub>4</sub> Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro Molecules
We have theoretically investigated nine unusual isomers of the molecular formula C<sub>5</sub>H<sub>4</sub> using coupled cluster (CC) and density functional theory (DFT) methods. These molecules possess non-classical structures consisting of two pyramidanes, three planar tet...
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2023-06-01
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| author | Sayon Satpati Tarun Roy Sandip Giri Anakuthil Anoop Venkatesan S. Thimmakondu Subhas Ghosal |
| author_facet | Sayon Satpati Tarun Roy Sandip Giri Anakuthil Anoop Venkatesan S. Thimmakondu Subhas Ghosal |
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| description | We have theoretically investigated nine unusual isomers of the molecular formula C<sub>5</sub>H<sub>4</sub> using coupled cluster (CC) and density functional theory (DFT) methods. These molecules possess non-classical structures consisting of two pyramidanes, three planar tetracoordinate carbon (<b>ptC</b>), and four spiro types of isomers. Both the pyramidanes (tetracyclo-[2.1.0.0<sup>1,3</sup>.0<sup>2,5</sup>]pentane; <b>py-1</b> and tricyclo-[2.1.0.0<sup>2,5</sup>]pentan-3-ylidene; <b>py-2</b>) are minima on the potential energy surface (PES) of C<sub>5</sub>H<sub>4</sub>. Among the three isomers containing ptC, (SP4)-spiro [2.2]pent-1-yne (<b>ptC-2</b>) is a minimum, whereas isomer, (SP4)-spiro [2.2]pent-1,4-diene (<b>ptC-1</b>) is a fourth-order saddle point, and (SP4)-sprio[2.2]pent-1,4-diylidene (<b>ptC-3</b>) is a transition state. The corresponding spiro isomers spiro[2.2]pent-1,4-diene (<b>spiro-1</b>), sprio[2.2]pent-1,4-diylidene (<b>spiro-3</b>) and spiro[2.2]pent-4-en-1-ylidene (<b>spiro-4</b>) are local minima, except spiro[2.2]pent-1-yne (<b>spiro-2</b>), which is a second-order saddle point. All relative energies are calculated with respect to the global minimum (pent-1,3-diyne; <b>1</b>) at the CCSD(T)/cc-pVTZ level of theory. Quantum chemical calculations have been performed to analyze the bonding and topological configurations for all these nine isomers at the B3LYP/6-311+G(d,p) level of theory for a better understanding of their corresponding electronic structures. <b>ptC-2</b> was found to be thermodynamically more stable than its corresponding spiro counterpart (<b>spiro-2</b>) and possesses a high dipole moment (μ = 4.64 D). The stability of the <b>ptC</b> structures with their higher spin states has been discussed. |
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| spelling | doaj.art-cad335c2c50644638065ec795baa5e882023-11-18T09:15:42ZengMDPI AGAtoms2218-20042023-06-011169610.3390/atoms11060096Structure and Bonding Patterns in C<sub>5</sub>H<sub>4</sub> Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro MoleculesSayon Satpati0Tarun Roy1Sandip Giri2Anakuthil Anoop3Venkatesan S. Thimmakondu4Subhas Ghosal5Department of Chemistry, National Institute of Technology Durgapur, M G Avenue, Durgapur 713209, West Bengal, IndiaDepartment of Chemistry, National Institute of Technology Durgapur, M G Avenue, Durgapur 713209, West Bengal, IndiaDepartment of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, IndiaDepartment of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721302, West Bengal, IndiaDepartment of Chemistry and Biochemistry, San Diego State University, San Diego, CA 92182-1030, USADepartment of Chemistry, National Institute of Technology Durgapur, M G Avenue, Durgapur 713209, West Bengal, IndiaWe have theoretically investigated nine unusual isomers of the molecular formula C<sub>5</sub>H<sub>4</sub> using coupled cluster (CC) and density functional theory (DFT) methods. These molecules possess non-classical structures consisting of two pyramidanes, three planar tetracoordinate carbon (<b>ptC</b>), and four spiro types of isomers. Both the pyramidanes (tetracyclo-[2.1.0.0<sup>1,3</sup>.0<sup>2,5</sup>]pentane; <b>py-1</b> and tricyclo-[2.1.0.0<sup>2,5</sup>]pentan-3-ylidene; <b>py-2</b>) are minima on the potential energy surface (PES) of C<sub>5</sub>H<sub>4</sub>. Among the three isomers containing ptC, (SP4)-spiro [2.2]pent-1-yne (<b>ptC-2</b>) is a minimum, whereas isomer, (SP4)-spiro [2.2]pent-1,4-diene (<b>ptC-1</b>) is a fourth-order saddle point, and (SP4)-sprio[2.2]pent-1,4-diylidene (<b>ptC-3</b>) is a transition state. The corresponding spiro isomers spiro[2.2]pent-1,4-diene (<b>spiro-1</b>), sprio[2.2]pent-1,4-diylidene (<b>spiro-3</b>) and spiro[2.2]pent-4-en-1-ylidene (<b>spiro-4</b>) are local minima, except spiro[2.2]pent-1-yne (<b>spiro-2</b>), which is a second-order saddle point. All relative energies are calculated with respect to the global minimum (pent-1,3-diyne; <b>1</b>) at the CCSD(T)/cc-pVTZ level of theory. Quantum chemical calculations have been performed to analyze the bonding and topological configurations for all these nine isomers at the B3LYP/6-311+G(d,p) level of theory for a better understanding of their corresponding electronic structures. <b>ptC-2</b> was found to be thermodynamically more stable than its corresponding spiro counterpart (<b>spiro-2</b>) and possesses a high dipole moment (μ = 4.64 D). The stability of the <b>ptC</b> structures with their higher spin states has been discussed.https://www.mdpi.com/2218-2004/11/6/96C<sub>5</sub>H<sub>4</sub>DFTcoupled clusterpyramidaneptCspiro |
| spellingShingle | Sayon Satpati Tarun Roy Sandip Giri Anakuthil Anoop Venkatesan S. Thimmakondu Subhas Ghosal Structure and Bonding Patterns in C<sub>5</sub>H<sub>4</sub> Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro Molecules Atoms C<sub>5</sub>H<sub>4</sub> DFT coupled cluster pyramidane ptC spiro |
| title | Structure and Bonding Patterns in C<sub>5</sub>H<sub>4</sub> Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro Molecules |
| title_full | Structure and Bonding Patterns in C<sub>5</sub>H<sub>4</sub> Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro Molecules |
| title_fullStr | Structure and Bonding Patterns in C<sub>5</sub>H<sub>4</sub> Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro Molecules |
| title_full_unstemmed | Structure and Bonding Patterns in C<sub>5</sub>H<sub>4</sub> Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro Molecules |
| title_short | Structure and Bonding Patterns in C<sub>5</sub>H<sub>4</sub> Isomers: Pyramidane, Planar Tetracoordinate Carbon, and Spiro Molecules |
| title_sort | structure and bonding patterns in c sub 5 sub h sub 4 sub isomers pyramidane planar tetracoordinate carbon and spiro molecules |
| topic | C<sub>5</sub>H<sub>4</sub> DFT coupled cluster pyramidane ptC spiro |
| url | https://www.mdpi.com/2218-2004/11/6/96 |
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