scholarly journals The Importance of Strain (Preorganization) in Beryllium Bonds

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5876
Author(s):  
Ibon Alkorta ◽  
José Elguero ◽  
Josep M. Oliva-Enrich ◽  
Manuel Yáñez ◽  
Otilia Mó ◽  
...  
Keyword(s):  
Decomposition Analysis ◽  
Orbital Energy ◽  
Strong Interactions ◽  
Energy Decomposition Analysis ◽  
Lewis Bases ◽  
Dissociation Energies ◽  
Polarization Term ◽  
Acidic Nature ◽  
Intermolecular Distances ◽  
Derivatives Of

In order to explore the angular strain role on the ability of Be to form strong beryllium bonds, a theoretical study of the complexes of four beryllium derivatives of orthocloso-carboranes with eight molecules (CO, N2, NCH, CNH, OH2, SH2, NH3, and PH3) acting as Lewis bases has been carried out at the G4 computational level. The results for these complexes, which contain besides Be other electron-deficient elements, such as B, have been compared with the analogous ones formed by three beryllium salts (BeCl2, CO3Be and SO4Be) with the same set of Lewis bases. The results show the presence of large and positive values of the electrostatic potential associated to the beryllium atoms in the isolated four beryllium derivatives of ortho-carboranes, evidencing an intrinsically strong acidic nature. In addition, the LUMO orbital in these systems is also associated to the beryllium atom. These features led to short intermolecular distances and large dissociation energies in the complexes of the beryllium derivatives of ortho-carboranes with the Lewis bases. Notably, as a consequence of the special framework provided by the ortho-carboranes, some of these dissociation energies are larger than the corresponding beryllium bonds in the already strongly bound SO4Be complexes, in particular for N2 and CO bases. The localized molecular orbital energy decomposition analysis (LMOEDA) shows that among the attractive terms associated with the dissociation energy, the electrostatic term is the most important one, except for the complexes with the two previously mentioned weakest bases (N2 and CO), where the polarization term dominates. Hence, these results contribute to further confirm the importance of bending on the beryllium environment leading to strong interactions through the formation of beryllium bonds.

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

scholarly journals Hydrogen vs. Halogen Bonds in 1-Halo-Closo-Carboranes

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2163 ◽  
Author(s):  
Ibon Alkorta ◽  
Jose Elguero ◽  
Josep M. Oliva-Enrich
Keyword(s):  
Electron Density ◽  
Halogen Bond ◽  
Noncovalent Interactions ◽  
Decomposition Analysis ◽  
Binding Energies ◽  
Energy Decomposition Analysis ◽  
Bond Critical Point ◽  
Total Energy Density ◽  
Comparison Of The Results ◽  
Intermolecular Distances

A theoretical study of the hydrogen bond (HB) and halogen bond (XB) complexes between 1-halo-closo-carboranes and hydrogen cyanide (NCH) as HB and XB probe has been carried out at the MP2 computational level. The energy results show that the HB complexes are more stable than the XBs for the same system, with the exception of the isoenergetic iodine derivatives. The analysis of the electron density with the quantum theory of atoms in molecules (QTAIM) shows the presence of a unique intermolecular bond critical point with the typical features of weak noncovalent interactions (small values of the electron density and positive Laplacian and total energy density). The natural energy decomposition analysis (NEDA) of the complexes shows that the HB and XB complexes are dominated by the charge-transfer and polarization terms, respectively. The work has been complemented with a search in the CSD database of analogous complexes and the comparison of the results, with those of the 1-halobenzene:NCH complexes showing smaller binding energies and larger intermolecular distances as compared to the 1-halo-closo-carboranes:NCH complexes.

On the Nature of Halide-Water Interactions: Insights from Many-Body Representations and Density Functional Theory

2019 ◽  
Author(s):  
Brandon B. Bizzarro ◽  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Density Functional Theory ◽  
Charge Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Interaction Energies ◽  
Many Body ◽  
Functional Theory

<div> <div> <div> <p>Interaction energies of halide-water dimers, X<sup>-</sup>(H<sub>2</sub>O), and trimers, X<sup>-</sup>(H<sub>2</sub>O)<sub>2</sub>, with X = F, Cl, Br, and I, are investigated using various many-body models and exchange-correlation functionals selected across the hierarchy of density functional theory (DFT) approximations. Analysis of the results obtained with the many-body models demonstrates the need to capture important short-range interactions in the regime of large inter-molecular orbital overlap, such as charge transfer and charge penetration. Failure to reproduce these effects can lead to large deviations relative to reference data calculated at the coupled cluster level of theory. Decompositions of interaction energies carried out with the absolutely localized molecular orbital energy decomposition analysis (ALMO-EDA) method demonstrate that permanent and inductive electrostatic energies are accurately reproduced by all classes of XC functionals (from generalized gradient corrected (GGA) to hybrid and range-separated functionals), while significant variance is found for charge transfer energies predicted by different XC functionals. Since GGA and hybrid XC functionals predict the most and least attractive charge transfer energies, respectively, the large variance is likely due to the delocalization error. In this scenario, the hybrid XC functionals are then expected to provide the most accurate charge transfer energies. The sum of Pauli repulsion and dispersion energies are the most varied among the XC functionals, but it is found that a correspondence between the interaction energy and the ALMO EDA total frozen energy may be used to determine accurate estimates for these contributions. </p> </div> </div> </div>

Assessing Many-Body Effects of Water Self-Ions. II: H3O+(H2O)n Clusters

2019 ◽  
Author(s):  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Decomposition Analysis ◽  
Body Representation ◽  
Orbital Energy ◽  
Coupled Cluster ◽  
Energy Decomposition Analysis ◽  
Many Body ◽  
Systematic Analysis ◽  
Interaction Terms ◽  
Many Body Effects ◽  
Many Body Interactions

<div> <div> <div> <p>The importance of many-body effects in the hydration of the hydronium ion (H3O+) is investigated through a systematic analysis of the many-body expansion of the interaction energy carried out at the coupled cluster level of theory for the low-lying isomers of H3O+(H2O)n clusters with n = 1 − 5. This is accomplished by partitioning individual fragments extracted from the whole clusters into “groups” that are classified by both the number of H3O+ and water molecules and the H-bonding connectivity within a given fragment. Effects due to the presence of the Zundel ion, (H5O2)+, are analyzed by further partitioning fragment groups by the “context” of their parent clusters. With the aid of the absolutely localized molecular orbital energy decomposition analysis (ALMO EDA), this structure-based partitioning is found to largely correlate with the character of different many-body interactions, such as cooperative and anticooperative hydrogen-bonding, within each fragment. This analysis emphasizes the importance of a many-body representation of inductive electrostatics and charge transfer in modeling the hydration of an excess proton in water. The comparison between the reference coupled cluster many-body interaction terms with the corresponding values obtained with various exchange-correlation functionals demonstrates that many of these functionals yield an unbalanced treatment of the H3O+(H2O)n configuration space. </p> </div> </div> </div>

Assessing Many-Body Effects of Water Self-Ions. II: H3O+(H2O)n Clusters

2019 ◽  
Author(s):  
Colin K. Egan ◽  
Francesco Paesani
Keyword(s):  
Decomposition Analysis ◽  
Body Representation ◽  
Orbital Energy ◽  
Coupled Cluster ◽  
Energy Decomposition Analysis ◽  
Many Body ◽  
Systematic Analysis ◽  
Interaction Terms ◽  
Many Body Effects ◽  
Many Body Interactions

<div> <div> <div> <p>The importance of many-body effects in the hydration of the hydronium ion (H3O+) is investigated through a systematic analysis of the many-body expansion of the interaction energy carried out at the coupled cluster level of theory for the low-lying isomers of H3O+(H2O)n clusters with n = 1 − 5. This is accomplished by partitioning individual fragments extracted from the whole clusters into “groups” that are classified by both the number of H3O+ and water molecules and the H-bonding connectivity within a given fragment. Effects due to the presence of the Zundel ion, (H5O2)+, are analyzed by further partitioning fragment groups by the “context” of their parent clusters. With the aid of the absolutely localized molecular orbital energy decomposition analysis (ALMO EDA), this structure-based partitioning is found to largely correlate with the character of different many-body interactions, such as cooperative and anticooperative hydrogen-bonding, within each fragment. This analysis emphasizes the importance of a many-body representation of inductive electrostatics and charge transfer in modeling the hydration of an excess proton in water. The comparison between the reference coupled cluster many-body interaction terms with the corresponding values obtained with various exchange-correlation functionals demonstrates that many of these functionals yield an unbalanced treatment of the H3O+(H2O)n configuration space. </p> </div> </div> </div>

The Dewar–Chatt–Duncanson model reversed — Bonding analysis of group-10 complexes [(PMe3)2M–EX3] (M = Ni, Pd, Pt; E = B, Al, Ga, In, Tl; X = H, F, Cl, Br, I)

2009 ◽  
Vol 87 (10) ◽  
pp. 1470-1479 ◽  
Author(s):  
Catharina Goedecke ◽  
Pierre Hillebrecht ◽  
Till Uhlemann ◽  
Robin Haunschild ◽  
Gernot Frenking
Keyword(s):  
Metal Atom ◽  
Decomposition Analysis ◽  
Basis Sets ◽  
Energy Decomposition Analysis ◽  
Bond Dissociation Energies ◽  
Energy Decomposition ◽  
Group 13 ◽  
Orbital Interactions ◽  
Bond Dissociation ◽  
Dissociation Energies

Quantum chemical calculations using BP86 with TZ2P basis sets were carried out to elucidate the structures and the bond–bond dissociation energies of the donor–acceptor complexes [(PMe3)2M–EX3] with X = H, F, Cl, Br, I; E = B, Al, Ga, In, Tl; and M = Ni, Pd, Pt. The nature of the metal–ligand bond was investigated with an energy decomposition analysis. The geometry optimizations gave for most compounds T-shaped structures with nearly linear P–M–P angles where the EX3 ligand has either a staggered or eclipsed conformation with respect to the PMP plane. The energy differences between the conformations are very small which means that there is nearly free rotation about the M–EX3 axis. The equilibrium structures of eight nickel compounds have a distorted geometry where one E–X bond is engaged in attractive interactions with the metal atom which yields a distorted square-planar arrangement of the metal atom. The complex [(PMe3)2Ni–TlI3] exhibits two attractive interactions between Tl–I bonds and the metal which features a five-coordinated metal atom. The calculated bond dissociation energies show that the boron complexes exhibit a different trend for the De values than the heavier group-13 homologues. The results for the Pd and Pt complexes suggest that the [(PMe3)2M–BX3] bond strength increases with F < Cl < Br < I < H which means that the BH3 ligands are the most strongly bonded Lewis acids and BF3 is the most weakly bonded species . The trend for the heavier group-13 complexes [(PMe3)2M–EX3] where E = Al, Ga, In, Tl follows the opposite order F > Cl > Br > I > H. The energy decomposition analysis of the M–EX3 bonds indicates a substantial π contribution of between 12.7% and 30.3% to the total orbital interactions. There is no direct correlation between the strength of the orbital interactions or any of the other energy terms ΔEelstat or ΔEPauli which correlates with the total interaction energy. The bond dissociation energy of the EX3 ligands after breaking the M–EX3 bonds is quite large. It is shown that the intrinsic strength of the M–EX3 bonds is much larger than the BDEs and that the trends of ΔEint and De are not always the same. The EX3 ligands in [(PMe3)2M–BX3] always carry a large negative charge.

scholarly journals A comparative study of energetics of ferrocenium and ferrocene

2018 ◽  
Author(s):  
Shawkat Islam ◽  
Feng Wang
Keyword(s):  
Decomposition Analysis ◽  
Open Shell ◽  
Electrostatic Energy ◽  
Orbital Energy ◽  
Energy Decomposition Analysis ◽  
Quantum Mechanical ◽  
High Symmetry ◽  
Energy Decomposition ◽  
Molecular Electronic ◽  
Repulsive Energy

Ferrocenium (Fc+) inherits a number of molecular/electronic properties from the neutral counterparts’ ferrocene (Fc) including the high symmetry. Both Fc+ and Fc prefer the eclipsed structure (D5h) over the staggered structure (D5d) by an energy of 0.36 kcal·mol-1. The present study using the recently developed excess orbital energy spectrum (EOES) shows that the open shell Fc+ cation exhibits similar conformer dependent configurational changes to the neutral Fc conformer pair. A further energy decomposition analysis (EDA) discloses that the reasons for the preferred structures are different between Fc+ and Fc. The dominant differentiating energy between the Fc+ conformers is the electrostatic energy (EEstat), whereas in neutral Fc, it is the quantum mechanical Pauli repulsive energy (EPauli). Within the D5h conformer of Fc+, the EOES reveals that the -electrons of Fc+ experience more substantial conformer dependent energy changes than the -electrons (assumed the hole is in a β orbital).

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