scholarly journals Bonding Analysis in [1.1.1]Propellane and [1.1.1]Bicyclopentane Using Orbital Forces. The Myth of the “Inverted Bond”

2018 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-García ◽  
Franck Fuster ◽  
François Volatron ◽  
Patrick Chaquin
Keyword(s):  
Triplet State ◽  
Total Energy ◽  
Molecular Orbital ◽  
Physical Basis ◽  
Bond Energies ◽  
Bonding Analysis

The properties of the “inverted bond” in [1.1.1]propellane are investigated by two methods. Firstly we study H3C-C models of C-C bonds with frozen HCC angles reproducing the constraints of various degrees of “inversion”. Secondly, the molecular orbital (MO) properties of [1.1.1]propellane and [1.1.1]bicyclopentane are analyzed with the help of orbital forces as a criterion of bonding/antibonding character and as a basis to evaluate in-situ bond energies. Triplet state of propellane and cationic states of propellane and bicyclopentane are also considered to comfort the bonding/antibonding character of MOs in the parent molecules. Both approaches shows an essentially nonbonding or slightly repulsive character of the sigma central CC interaction in propellane: the so-called ‘inverted’ bond, as resulting from a sigma overlap of the two s-p hybrids by their smaller lobes, appears devoid of physical basis. The bonding of central CC in propellane is thus only due to pi-type MOs (also called ‘banana’ MOs or ‘bridge’ MOs) and its total energy is evaluated to ca. 60 kcal/mol. In bicyclopentane, despite a strong sigma-type repulsion, a weak bonding (20 kcal/mol) exists between both central CC, also due to pi-type interactions, though no formal bond is present

scholarly journals The ‘Inverted Bond’ revisited. Analysis of ‘in silico’ models and of [1.1.1]Propellane using Orbital Forces

2019 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-García ◽  
Franck Fuster ◽  
François Volatron ◽  
Patrick Chaquin
Keyword(s):  
Total Energy ◽  
Molecular Orbital ◽  
In Silico ◽  
Bond Energies ◽  
Parent Molecule ◽  
Ca 50 ◽  
In Silico Models ◽  
Mo Theory

<div>This article dwells on the nature of “inverted bonds”, which make reference to the σ interaction between two s-p hybrids by their smaller lobes, and their presence in [1.1.1]propellane <b>1</b>. Firstly we study H 3 C-C models of C-C bonds with frozen HCC angles reproducing the constraints of various degrees of “inversion”. Secondly, the molecular orbital (MO) properties of [1.1.1]propellane <b>1</b> and [1.1.1]bicyclopentane <b>2</b> are analyzed with the help of orbital forces as a criterion of bonding/antibonding character and as a basis to evaluate bond energies. Triplet and cationic state of <b>1</b> species are also considered to confirm the bonding/antibonding character of MOs in the parent molecule. These approaches show an essentially non-bonding character of the σ central CC interaction in propellane. Within MO theory, this bonding is thus only due to π-type MOs (also called ‘banana’ MOs or ‘bridge’ MOs) and its total energy is evaluated to ca. 50 kcal/mol. In bicyclopentane <b>2</b>, despite a strong σ-type repulsion, a weak bonding (15-20 kcal/mol) exists between both central CC, also due to π-type interactions, though no bond is present in the Lewis structure. Overall, the so-called ‘inverted’ bond, as resulting from a σ overlap of the two s-p hybrids by their smaller lobes, appears highly questionable.</div>

scholarly journals The ‘Inverted Bond’ revisited. Analysis of ‘in silico’ models and of [1.1.1]Propellane using Orbital Forces

2019 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-García ◽  
Franck Fuster ◽  
François Volatron ◽  
Patrick Chaquin
Keyword(s):  
Total Energy ◽  
Molecular Orbital ◽  
In Silico ◽  
Bond Energies ◽  
Parent Molecule ◽  
Ca 50 ◽  
In Silico Models ◽  
Mo Theory

<div>This article dwells on the nature of “inverted bonds”, which make reference to the σ interaction between two s-p hybrids by their smaller lobes, and their presence in [1.1.1]propellane <b>1</b>. Firstly we study H 3 C-C models of C-C bonds with frozen HCC angles reproducing the constraints of various degrees of “inversion”. Secondly, the molecular orbital (MO) properties of [1.1.1]propellane <b>1</b> and [1.1.1]bicyclopentane <b>2</b> are analyzed with the help of orbital forces as a criterion of bonding/antibonding character and as a basis to evaluate bond energies. Triplet and cationic state of <b>1</b> species are also considered to confirm the bonding/antibonding character of MOs in the parent molecule. These approaches show an essentially non-bonding character of the σ central CC interaction in propellane. Within MO theory, this bonding is thus only due to π-type MOs (also called ‘banana’ MOs or ‘bridge’ MOs) and its total energy is evaluated to ca. 50 kcal/mol. In bicyclopentane <b>2</b>, despite a strong σ-type repulsion, a weak bonding (15-20 kcal/mol) exists between both central CC, also due to π-type interactions, though no bond is present in the Lewis structure. Overall, the so-called ‘inverted’ bond, as resulting from a σ overlap of the two s-p hybrids by their smaller lobes, appears highly questionable.</div>

The molecular orbital theory of chemical valency XX. The energy in higher approximations

1955 ◽  
Vol 230 (1182) ◽  
pp. 424-428 ◽  
Keyword(s):  
Wave Function ◽  
Total Energy ◽  
Molecular Orbital ◽  
Molecular Orbital Theory ◽  
Bond Energies ◽  
Orbital Theory ◽  
Conjugated Molecules ◽  
Approximate Wave Function ◽  
Approximate Wave

The equations determining the optimum orbitals in a many-determinant approximate wave function are given and their relation to the total energy considered. As expected, the form of the energy shows that bond energies will be nearly additive in non-conjugated molecules as long as they are not strongly polar, but that this will not be so for conjugated molecules.

The ‘Inverted Bond’ revisited. Analysis of ‘in silico’ models and of [1.1.1]Propellane using Orbital Forces

2019 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-García ◽  
Franck Fuster ◽  
François Volatron ◽  
Patrick Chaquin
Keyword(s):  
Total Energy ◽  
Molecular Orbital ◽  
In Silico ◽  
Bond Energies ◽  
Parent Molecule ◽  
Ca 50 ◽  
In Silico Models ◽  
Mo Theory

<div>This article dwells on the nature of “inverted bonds”, which make reference to the σ interaction between two s-p hybrids by their smaller lobes, and their presence in [1.1.1]propellane <b>1</b>. Firstly we study H 3 C-C models of C-C bonds with frozen HCC angles reproducing the constraints of various degrees of “inversion”. Secondly, the molecular orbital (MO) properties of [1.1.1]propellane <b>1</b> and [1.1.1]bicyclopentane <b>2</b> are analyzed with the help of orbital forces as a criterion of bonding/antibonding character and as a basis to evaluate bond energies. Triplet and cationic state of <b>1</b> species are also considered to confirm the bonding/antibonding character of MOs in the parent molecule. These approaches show an essentially non-bonding character of the σ central CC interaction in propellane. Within MO theory, this bonding is thus only due to π-type MOs (also called ‘banana’ MOs or ‘bridge’ MOs) and its total energy is evaluated to ca. 50 kcal/mol. In bicyclopentane <b>2</b>, despite a strong σ-type repulsion, a weak bonding (15-20 kcal/mol) exists between both central CC, also due to π-type interactions, though no bond is present in the Lewis structure. Overall, the so-called ‘inverted’ bond, as resulting from a σ overlap of the two s-p hybrids by their smaller lobes, appears highly questionable.</div>

scholarly journals The ‘Inverted Bond’ revisited. Analysis of ‘in silico’ models and of [1.1.1]Propellane using Orbital Forces

2019 ◽  
Author(s):  
Rubén Laplaza ◽  
Julia Contreras-García ◽  
Franck Fuster ◽  
François Volatron ◽  
Patrick Chaquin
Keyword(s):  
Total Energy ◽  
Molecular Orbital ◽  
In Silico ◽  
Bond Energies ◽  
Parent Molecule ◽  
Ca 50 ◽  
In Silico Models ◽  
Mo Theory

<div>This article dwells on the nature of “inverted bonds”, which make reference to the σ interaction between two s-p hybrids by their smaller lobes, and their presence in [1.1.1]propellane <b>1</b>. Firstly we study H 3 C-C models of C-C bonds with frozen HCC angles reproducing the constraints of various degrees of “inversion”. Secondly, the molecular orbital (MO) properties of [1.1.1]propellane <b>1</b> and [1.1.1]bicyclopentane <b>2</b> are analyzed with the help of orbital forces as a criterion of bonding/antibonding character and as a basis to evaluate bond energies. Triplet and cationic state of <b>1</b> species are also considered to confirm the bonding/antibonding character of MOs in the parent molecule. These approaches show an essentially non-bonding character of the σ central CC interaction in propellane. Within MO theory, this bonding is thus only due to π-type MOs (also called ‘banana’ MOs or ‘bridge’ MOs) and its total energy is evaluated to ca. 50 kcal/mol. In bicyclopentane <b>2</b>, despite a strong σ-type repulsion, a weak bonding (15-20 kcal/mol) exists between both central CC, also due to π-type interactions, though no bond is present in the Lewis structure. Overall, the so-called ‘inverted’ bond, as resulting from a σ overlap of the two s-p hybrids by their smaller lobes, appears highly questionable.</div>

scholarly journals Real-Space In Situ Bond Energies: Toward A Consistent Energetic Definition of Bond Strength

2018 ◽  
Vol 24 (36) ◽  
pp. 9101-9112 ◽  
Author(s):  
Daniel Menéndez-Crespo ◽  
Aurora Costales ◽  
Evelio Francisco ◽  
Ángel Martín Pendás
Keyword(s):  
Bond Strength ◽  
Real Space ◽  
Bond Energies ◽  
Definition Of

A Study On The Thermal Decomposition of Ba(tmhd)2 and Sr(tmhd)2

1995 ◽  
Vol 415 ◽  
Author(s):  
Hyun-Kyu Ryu ◽  
Jae Hyun Han ◽  
Sang Heup Moon
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Thermogravimetric Analysis ◽  
Metal Atom ◽  
Bond Energies ◽  
Partial Decomposition ◽  
Temperature Range ◽  
Long Period

ABSTRACTDecomposition of Sr(tmhd)2 and Ba(tmhd)2 was investigated by thermogravimetric analysis, in-situ FTIR, and mass spectrometry. Both compounds decomposed following 3 steps: 1) decomposition of the ligands, 2) simultaneous vaporization and partial decomposition of metal-organics, and 3) decomposition of the vaporized metal-organics which existed as the oligomeric species.The Sr source decomposed at lower temperatures and in a narrower temperature range than the Ba source. Also, the gaseous oligomeric species from the Sr source decomposed relatively quickly while the corresponding species from the Ba source decomposed slowly over a long period. Such a difference between the two compounds is due to different bond energies between the metal atom and the ligands, as indicated by our FTIR results.

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