scholarly journals Perturbing the O–H…O Hydrogen Bond in 1-oxo-3-hydroxy-2-propene

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3086
Author(s):  
Ibon Alkorta ◽  
José Elguero ◽  
Janet E. Del Bene
Keyword(s):  
Potential Energy Surfaces ◽  
Correlation Coefficients ◽  
Binding Energies ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Transition Structures ◽  
Equilibrium Structures ◽  
Acid Potential ◽  
Energy Surfaces ◽  
Spin Spin Coupling

Ab initio MP2/aug’-cc-pVTZ calculations have been carried out to identify and characterize equilibrium structures and transition structures on the 1-oxo-3-hydroxy-2-propene: Lewis acid potential energy surfaces, with the acids LiH, LiF, BeH2, and BeF2. Two equilibrium structures, one with the acid interacting with the C=O group and the other with the interaction occurring at the O–H group, exist on all surfaces. These structures are separated by transition structures that present the barriers to the interconversion of the two equilibrium structures. The structures with the acid interacting at the C=O group have the greater binding energies. Since the barriers to convert the structures with interaction occurring at the O–H group are small, only the isomers with interaction occurring at the C=O group could be experimentally observed, even at low temperatures. Charge-transfer energies were computed for equilibrium structures, and EOM-CCSD spin–spin coupling constants 2hJ(O–O), 1hJ(H–O), and 1J(O–H) were computed for equilibrium and transition structures. These coupling constants exhibit a second-order dependence on the corresponding distances, with very high correlation coefficients.

scholarly journals N…C and S…S Interactions in Complexes, Molecules, and Transition Structures HN(CH)SX:SCO, for X = F, Cl, NC, CCH, H, and CN

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3232
Author(s):  
Janet E. Del Bene ◽  
Ibon Alkorta ◽  
José Elguero
Keyword(s):  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Second Order ◽  
Binding Energies ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Order Dependence ◽  
Transition Structures ◽  
Bond Charge ◽  
Energy Surfaces

Ab initio Møller–Plesset perturbation theory (MP2)/aug’-cc-pVTZ calculations have been carried out in search of complexes, molecules, and transition structures on HN(CH)SX:SCO potential energy surfaces for X = F, Cl, NC, CCH, H, and CN. Equilibrium complexes on these surfaces have C1 symmetry, but these have binding energies that are no more than 0.5 kJ·mol–1 greater than the corresponding Cs complexes which are vibrationally averaged equilibrium complexes. The binding energies of these span a narrow range and are independent of the N–C distance across the tetrel bond, but they exhibit a second-order dependence on the S–S distance across the chalcogen bond. Charge-transfer interactions stabilize all of these complexes. Only the potential energy surfaces HN(CH)SF:SCO and HN(CH)SCl:SCO have bound molecules that have short covalent N–C bonds and significantly shorter S…S chalcogen bonds compared to the complexes. Equation-of-motion coupled cluster singles and doubles (EOM-CCSD) spin-spin coupling constants 1tJ(N–C) for the HN(CH)SX:SCO complexes are small and exhibit no dependence on the N–C distance, while 1cJ(S–S) exhibit a second-order dependence on the S–S distance, increasing as the S–S distance decreases. Coupling constants 1tJ(N–C) and 1cJ(S–S) as a function of the N–C and S–S distances, respectively, in HN(CH)SF:SCO and HN(CH)SCl:SCO increase in the transition structures and then decrease in the molecules. These changes reflect the changing nature of the N…C and S…S bonds in these two systems.

Using one halogen bond to change the nature of a second bond in ternary complexes with P⋯Cl and F⋯Cl halogen bonds

2017 ◽  
Vol 203 ◽  
pp. 29-45 ◽  
Author(s):  
Janet E. Del Bene ◽  
Ibon Alkorta ◽  
José Elguero
Keyword(s):  
Halogen Bond ◽  
Synergistic Effects ◽  
Ternary Complexes ◽  
Binding Energies ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Halogen Bonds ◽  
Binary Complexes ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

Ab initio MP2/aug’-cc-pVTZ calculations have been carried out to determine the effect of the presence of one halogen bond on the nature of the other in ternary complexes H2XP:ClF:ClH and H2XP:ClF:ClF, for X = F, Cl, H, NC, and CN. The P⋯Cl bonds remain chlorine-shared halogen bonds in the ternary complexes H2XP:ClF:ClH, although the degree of chlorine sharing increases relative to the corresponding binary complexes. The F⋯Cl bonds in the ternary complexes remain traditional halogen bonds. The binding energies of the complexes H2XP:ClF:ClH increase relative to the corresponding binary complexes, and nonadditivities of binding energies are synergistic. In contrast, the presence of two halogen bonds in the ternary complexes H2XP:ClF:ClF has a dramatic effect on the nature of these bonds in the four most strongly bound complexes. In these, chlorine transfer occurs across the P⋯Cl halogen bond to produce complexes represented as (H2XP–Cl)+:−(F:ClF). In the ion-pair, the cation is also halogen bonded to the anion by a Cl⋯F− halogen bond, while the anion is stabilized by an −F⋯Cl halogen bond. The central ClF molecule no longer exists as a molecule. The binding energies of the ternary H2XP:ClF:ClF complexes are significantly greater than the binding energies of the H2XP:ClF:ClH complexes, and nonadditivities exhibit large synergistic effects. The Wiberg bond indexes for the complexes H2XP:ClF, H2XP:ClF:ClH, and H2XP:ClF:ClF, and the cations (H2XP–Cl)+ reflect the changes in the P–Cl and Cl–F bonds. Similarly, EOM-CCSD spin–spin coupling constants are also consistent with the changes in these same bonds. In particular, 1xJ(P–Cl) in H2XP:ClF complexes becomes 1J(P–Cl) in the ternary complexes with chlorine-transferred halogen bonds. A plot of these coupling constants shows a change in the curvature of the trendline as chlorine-shared halogen bonds in H2XP:ClF:ClH become chlorine-transferred halogen bonds in H2XP:ClF:ClF. 1xJ(F–Cl) coupling constants also reflect changes in the nature of F⋯Cl halogen bonds.

scholarly journals Photodynamics of clusters of the major components of the atmosphere

2004 ◽  
Vol 6 (2) ◽  
pp. 53-59 ◽  
Author(s):  
V. Aquilanti ◽  
M. Bartolomei ◽  
D. Cappelletti ◽  
E. Carmona-Novillo ◽  
F. Pirani
Keyword(s):  
Potential Energy Surfaces ◽  
Bound States ◽  
Second Virial Coefficient ◽  
Spin Coupling ◽  
Intermolecular Potential ◽  
Full Characterization ◽  
Energy Surfaces ◽  
Spin Spin Coupling

Weakly interacting molecules leading to collisional complexes, and to either stable or metastable dimers, potentially play an important role in molecular and surface physics, in astrophysics, in atmospheric photochemistry and physics, and climate. Accurate intermolecular potential energy surfaces for the major components of the atmosphere, leading to the characterization of theO2-O2,N2-N2andN2-O2dimers, have been obtained from the analysis of scattering experiments from our laboratory, also exploiting where available second virial coefficient data. A spherical harmonic expansion functional form describes the geometries of the dimers and accounts for the relative contributions to the intermolecular interaction from components of different nature. ForO2-O2, singlet, triplet and quintet surfaces are obtained accounting for the role of spin-spin coupling. The new surfaces allow the full characterization of structure and internal dynamics of the clusters, whose bound states and eigenfunctions are obtained by exact quantum mechanics. Besides the information on the nature of the bond, these results can be of use in modelling the role of dimers in air and the calculated rotovibrational levels provide a guidance for the analysis of spectra, thus establishing the ground for atmospheric monitorings. Reference is also briefly made to recent insight on the role of water.

scholarly journals Unusual Complexes of P(CH)3 with FH, ClH, and ClF

Molecules ◽  
2020 ◽  
Vol 25 (12) ◽  
pp. 2846
Author(s):  
Janet E. Del Bene ◽  
Ibon Alkorta ◽  
José Elguero
Keyword(s):  
Potential Energy Surfaces ◽  
Symmetry Axis ◽  
Dipole Moments ◽  
Binding Energies ◽  
Coupling Constants ◽  
Coupled Cluster ◽  
Halogen Bonds ◽  
Energy Component ◽  
P Values ◽  
Energy Surfaces

Ab initio MP2/aug’-cc-pVTZ calculations have been performed to determine the structures and binding energies of complexes formed by phosphatetrahedrane, P(CH)3, and HF, HCl, and ClF. Four types of complexes exist on the potential energy surfaces. Isomers A form at the P atom near the end of a P-C bond, B at a C-C bond, C at the centroid of the C-C-C ring along the C3 symmetry axis, and D at the P atom along the C3 symmetry axis. Complexes A and B are stabilized by hydrogen bonds when FH and ClH are the acids, and by halogen bonds when ClF is the acid. In isomers C, the dipole moments of the two monomers are favorably aligned but in D the alignment is unfavorable. For each of the monomers, the binding energies of the complexes decrease in the order A > B > C > D. The most stabilizing Symmetry Adapted Perturbation Theory (SAPT) binding energy component for the A and B isomers is the electrostatic interaction, while the dispersion interaction is the most stabilizing term for C and D. The barriers to converting one isomer to another are significantly higher for the A isomers compared to B. Equation of motion coupled cluster singles and doubles (EOM-CCSD) intermolecular coupling constants J(X-C) are small for both B and C isomers. J(X-P) values are larger and positive in the A isomers, negative in the B isomers, and have their largest positive values in the D isomers. Intramolecular coupling constants 1J(P-C) experience little change upon complex formation, except in the halogen-bonded complex FCl:P(CH3) A.

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