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Advanced Bonding Theories for Complexes
Published in Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu, Interdisciplinary Engineering Sciences, 2020
Ashutosh Kumar Dubey, Amartya Mukhopadhyay, Bikramjit Basu
Numerically the “Bond Order” of a molecule is one half of the difference between the number of electrons present in the bonding molecular orbitals and the antibonding molecular orbitals in a given molecule (viz., BO = ½ [no. of electrons in BMO − no. of electrons in ABMO]). Here, a positive BO, meaning more number of electrons located in BMO, as compared to ABMO, signifies a stable molecule (w.r.t. the associated atoms) or the fact that the formation of the molecule is energetically favored. In contrast, both zero and negative values for the BO implies that the concerned molecule is not stable and is not likely to form from the concerned atoms. Additionally, a greater positive value of the bond order indicates greater bond dissociation energy and a shorter bond length.
Metal Atom Reactions to form Novel Small Molecules
Published in Leonid Khriachtchev, Physics and Chemistry at Low Temperatures, 2019
Since the d electrons of tungsten are strongly involved in σ bonding, reactions of W with NH3 gave the major stable high-oxidation state product, N≡WH3, which is in agreement with the DFT-calculated energy profile.43 With the same rationale tungsten hexahydride, WH6, has been identified in W atom reactions with H2 in a neon matrix.21 Natural orbital occupations have been calculated for the N≡WH3 molecule.43 The effective bond order is 2.9, depending on the theoretical method employed, which is a fully developed triple bond.
Chemical Bond II: Molecular Orbitals
Published in Franco Battaglia, Thomas F. George, Understanding Molecules, 2018
Franco Battaglia, Thomas F. George
By defining the bond order as half the difference between the number of electrons in bonding orbitals and the number of electrons in anti-bonding orbitals, it turns out to be equal to 1 for the lithium, boron, and fluorine diatomic molecules, equal to 2 for the carbon and oxygen diatomic molecules, and equal to 3 for the nitrogen diatomic molecule. This justifies the result of Lewis scheme, which assigns single, double, or triple bonds to those molecules, which here have been found with a bond order equal to 1, 2, or 3. Helium and beryllium diatomic molecules, unstable according to Lewis, have a zero bond order.
A TDDFT study of some dinuclear compounds containing CpM(CO)3 or CpM(CO)2 groups
Published in Molecular Physics, 2020
Finally, the compounds like Cp(CO)3MM’(CO)5 (M=Mo, W; M’=Mn, Re) have also only one Cp ligand bonded to a Mo or W metal. The MM’ bond is considered as a single bond, with a theoretical bond order of 1. As with the other studied compounds, the Cp ligand is on the opposite side of the carbonyls. The five carbonyls in contact with M’ are arranged in a quasi-octahedral geometry, considering the M-M’ bond as the sixth ligand.
Reaction of Pentanol isomers with OH radical – A theoretical perspective
Published in Molecular Physics, 2018
Basheer Aazaad, Senthilkumar Lakshmipathi
The bond order of a particular bond may be measured through the strength of bond formation or bond breaking along the reaction pathway. To understand the nature of the reaction process, Wiberg bond indices were computed based on natural bond orbital analysis as implemented in Gaussian 09 program package.