Covalent vs. Dative Bonding in Carbon Monoxide and Other 10-Valence-Electron Diatomics

Valence bond theory (VB) was used to determine the extent and driving forces for covalent vs. dative bonding in 10-valence-electron diatomic molecules N<sub>2</sub>, CO, NO<sup>+</sup>, CN<sup>−</sup>, P<sub>2</sub>, SiS, PS<sup>+</sup>, an...

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Main Authors: Khadija Rizwan, John Morrison Galbraith
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/29/22/5396
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author Khadija Rizwan
John Morrison Galbraith
author_facet Khadija Rizwan
John Morrison Galbraith
author_sort Khadija Rizwan
collection DOAJ
description Valence bond theory (VB) was used to determine the extent and driving forces for covalent vs. dative bonding in 10-valence-electron diatomic molecules N<sub>2</sub>, CO, NO<sup>+</sup>, CN<sup>−</sup>, P<sub>2</sub>, SiS, PS<sup>+</sup>, and SiP<sup>−</sup>. VBSCF calculations were performed at the CCSD(T)/cc-pVDZ optimized geometries. The full triply bonded system included 20 VB structures. A separation of the σ and π space allowed for a subdivision of the full 20 structure set into sets of 8 and 3 for the π and σ systems, respectively. The smaller structure sets allowed for a more focused look at each type of bond. In situ bond energies for σ bonds, individual π bonds, the π system, and triple bonds follow expected trends. Our data shows that N<sub>2</sub> and P<sub>2</sub> have three covalent bonds whereas CO and SiS contain two covalent and one dative bond, and charged species NO<sup>+</sup>, CN<sup>−</sup>, PS<sup>+</sup>, and SiP<sup>−</sup> are a mixture of N<sub>2</sub> and CO type electronic arrangements, resulting in a nearly equal charge distribution. Dative bonds prefer to be in the π position due to enhanced σ covalency and π resonance. Both σ and π resonance energies depend on a balance of ionic strength, orbital compactness, σ constraints, and bond directionality. Resonance energy is a major contributor to bond strength, making up more than 50% of the π bonds in SiS and PS<sup>+</sup> (charge-shift bonds), and is greater than charge transfer in dative bonds.
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spelling doaj-art-7cd434f66939482c849d38a1bb8ae6b62025-08-20T02:48:01ZengMDPI AGMolecules1420-30492024-11-012922539610.3390/molecules29225396Covalent vs. Dative Bonding in Carbon Monoxide and Other 10-Valence-Electron DiatomicsKhadija Rizwan0John Morrison Galbraith1Department of Chemistry, Biochemistry and Physics, Marist College, 3399 North Road, Poughkeepsie, NY 12601, USADepartment of Chemistry, Biochemistry and Physics, Marist College, 3399 North Road, Poughkeepsie, NY 12601, USAValence bond theory (VB) was used to determine the extent and driving forces for covalent vs. dative bonding in 10-valence-electron diatomic molecules N<sub>2</sub>, CO, NO<sup>+</sup>, CN<sup>−</sup>, P<sub>2</sub>, SiS, PS<sup>+</sup>, and SiP<sup>−</sup>. VBSCF calculations were performed at the CCSD(T)/cc-pVDZ optimized geometries. The full triply bonded system included 20 VB structures. A separation of the σ and π space allowed for a subdivision of the full 20 structure set into sets of 8 and 3 for the π and σ systems, respectively. The smaller structure sets allowed for a more focused look at each type of bond. In situ bond energies for σ bonds, individual π bonds, the π system, and triple bonds follow expected trends. Our data shows that N<sub>2</sub> and P<sub>2</sub> have three covalent bonds whereas CO and SiS contain two covalent and one dative bond, and charged species NO<sup>+</sup>, CN<sup>−</sup>, PS<sup>+</sup>, and SiP<sup>−</sup> are a mixture of N<sub>2</sub> and CO type electronic arrangements, resulting in a nearly equal charge distribution. Dative bonds prefer to be in the π position due to enhanced σ covalency and π resonance. Both σ and π resonance energies depend on a balance of ionic strength, orbital compactness, σ constraints, and bond directionality. Resonance energy is a major contributor to bond strength, making up more than 50% of the π bonds in SiS and PS<sup>+</sup> (charge-shift bonds), and is greater than charge transfer in dative bonds.https://www.mdpi.com/1420-3049/29/22/5396valence bond theorydative bondscharge-shift bondingresonance energy
spellingShingle Khadija Rizwan
John Morrison Galbraith
Covalent vs. Dative Bonding in Carbon Monoxide and Other 10-Valence-Electron Diatomics
Molecules
valence bond theory
dative bonds
charge-shift bonding
resonance energy
title Covalent vs. Dative Bonding in Carbon Monoxide and Other 10-Valence-Electron Diatomics
title_full Covalent vs. Dative Bonding in Carbon Monoxide and Other 10-Valence-Electron Diatomics
title_fullStr Covalent vs. Dative Bonding in Carbon Monoxide and Other 10-Valence-Electron Diatomics
title_full_unstemmed Covalent vs. Dative Bonding in Carbon Monoxide and Other 10-Valence-Electron Diatomics
title_short Covalent vs. Dative Bonding in Carbon Monoxide and Other 10-Valence-Electron Diatomics
title_sort covalent vs dative bonding in carbon monoxide and other 10 valence electron diatomics
topic valence bond theory
dative bonds
charge-shift bonding
resonance energy
url https://www.mdpi.com/1420-3049/29/22/5396
work_keys_str_mv AT khadijarizwan covalentvsdativebondingincarbonmonoxideandother10valenceelectrondiatomics
AT johnmorrisongalbraith covalentvsdativebondingincarbonmonoxideandother10valenceelectrondiatomics