Rehybridization as a general mechanism for maximizing chemical and supramolecular bonding and a driving force for chemical reactions

Alabugin, Igor V.; Manoharan, Mariappan

doi:10.1002/jcc.20524

Cited by 77 publications

(82 citation statements)

References 179 publications

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“…Not only does the enhanced p-character render this C−H bond a better donor, 15,30 but it also decreases the C−C−H valence angle to ∼103°, leading to better alignment with the empty p orbital. The tendency for rehybridization should lead to a noticeable blue-shift in frequencies of the C−H bonds misaligned with the p z orbital.…”

Section: Resultsmentioning

confidence: 98%

tert-Butyl Carbocation in Condensed Phases: Stabilization via Hyperconjugation, Polarization, and Hydrogen Bonding

Stoyanov

Gomes

2015

J. Phys. Chem. A

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Despite the seeming similarity of the infrared (IR) spectra between tert-butyl cations (t-Bu(+)) in gaseous and condensed phases, there are important but so far unrecognized differences. The IR spectroscopic investigation of the hydrogen (H)-bonding of t-Bu(+) with the immediate environment together with the X-ray crystallographic data shows that one CH3 group of t-Bu(+) differs from the other two. In the Ar-tagged t-Bu(+) in vacuum, this group is predominantly polarized, showing three C-H stretch vibrations at 2913, 2965, and 3036 cm(-1) whereas the other two methyls are predominantly involved in strong hyperconjugation, yielding an intense triple IR band with a maximum at 2839 cm(-1). In a condensed phase, the bulk solvent effect promoted participation of the polarized CH3 group in additional hyperconjugation, decreasing its νCH3 frequencies by approximately 120 cm(-1), whereas frequencies of the other CH3 groups decreased by only ca. 4-10 cm(-1). This observation indicates that the influence of the condensed phase on t-Bu(+) stabilization is substantial. Thus, enhancement of H-bonding between t-Bu(+) and Anion(-) strengthens hyperconjugation and promotes further cation stabilization.

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Section: Resultsmentioning

confidence: 98%

tert-Butyl Carbocation in Condensed Phases: Stabilization via Hyperconjugation, Polarization, and Hydrogen Bonding

Stoyanov

Gomes

2015

J. Phys. Chem. A

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“…This is consistent with the increased double bond character and with the shorter C-N(sp 2 ) bond length in comparison with the C-N(sp 3 ). 29 Overall, in this CSD search the tested structures had too many differences in substituents to give any other conclusion on the dependence of pyramidalization on the length of the hydrogen bond. Somewhat better correlation was obtained (N = 57, R corr = 0.648) when an additional restriction was added: no substituents in the ortho position to the amino group ( Figure 5).…”

Section: Crystal Structure Of 34-diaminobenzamidinium Chloride (2)mentioning

confidence: 92%

Effect of Hydrogen Bonding on the Pyramidalization of the Amino Group: Structure of 3,4-diaminobenzamidinium Chloride

Stolić¹,

Bajić²,

Matković‐Čalogović³

2013

Croat. Chem. Acta

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Abstract. 3,4-diaminobenzamidinium was synthesized and spectroscopically and structurally characterized, both at room temperature and at 150 K. The crystal structure consists of two 3,4-diaminobenzamidinium cations and two chloride anions. The planar amidinium group is inclined by 35.35(5)° and 28.96(7)° in respect to the diaminobenzene moiety in the two crystallographically independent cations. The ions are interconnected by a large network of hydrogen bonds into a threedimensional structure. Pyramidalization of the amino group in relation to the hydrogen bond length in which the amino group is an acceptor is analized. Two amino groups are acceptors of N-H···N hydrogen bonds of 2.9565(14) Å and 2.9654(15) Å resulting in pyramidalization of 340(1)° and 337(1)°, respectively (the sum of the amino group bond angles is given as a measure of pyramidalization). A very weak hydrogen bond to one amino group results in a very flat pyramid (351(1)°), while one amino group is not acceptor of a hydrogen bonds and it is planar. The resonance effect has influence on the planar amino groups resulting in a shorter C-N(amino group) bond length than in the pyramidalized ones. (doi: 10.5562/cca2224) Keywords: pyramidalization of the amino group, 3,4-diaminobenzamidinium chloride, X-ray single crystal structure analysis

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“…However, the total net charge (q X + q H ) of HX in the complex is positive for the case of HCl, while -according to the largest absolute value of E NBO in the whole table -the CT should occur in the opposite direction. On the other hand, the Bader effective charges for HCl sum, as expected, to a negative quantity in this case.The creation of the hydrogen bond between the hydrogen halide and the fulborene molecule can be also -somewhat artificially -represented as a superposition of two competing effects: the so-called hyperconjugation74,75,156,157 and rehybridization [158][159][160]. The first effect is the transfer of of B 12 N 12 .…”

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confidence: 98%

Structure and Energetics of Complexes of B₁₂N₁₂ with Hydrogen Halides—SAPT(DFT) and MP2 Study

2015

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Molecular complexes of a fullerene analogue B12N12 with hydrogen halides (HCl, HBr, and HI) were studied with symmetry-adapted perturbation theory with density-functional theory applied for a description of monomers (SAPT(DFT)), Møller-Plesset theory to the second order (MP2), and its spin-component-scaled variant (SCS-MP2) in a limit of a complete basis set. For each halide five symmetry-distinct minimum structures of the complex have been found on the potential energy hypersurface, with interaction energies ranging from -6 to -18 kJ/mol. The natural bond orbital and the atom-in-molecules analysis of noncovalent bonds resulted in a division of these configurations into three categories: hydrogen-bonded, halogen-bonded, and those of a mixed type, involving simultaneously a hydrogen bonding and a π-hole bonding between halogen and boron atoms. A comparison of various approaches for the calculation of interaction energies shows that the SCS-MP2 supermolecular method gives results which are in a close agreement with SAPT(DFT), while the MP2 interaction energies are systematically more negative than the SAPT values. The ability of the B12N12 nanocage to bind hydrogen halides through several active sites on its surface puts under question the selectivity of the binding necessary in crystal engineering, especially for the hydrogen bromide and hydrogen iodide cases, which show small differences in stabilization energies for their minimum structures. The directionality of noncovalent bonds is explained on grounds of the anisotropy of some SAPT components, like electrostatics and induction, as well as by the σ-hole and π-hole models.

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Rehybridization as a general mechanism for maximizing chemical and supramolecular bonding and a driving force for chemical reactions

Cited by 77 publications

References 179 publications

tert-Butyl Carbocation in Condensed Phases: Stabilization via Hyperconjugation, Polarization, and Hydrogen Bonding

tert-Butyl Carbocation in Condensed Phases: Stabilization via Hyperconjugation, Polarization, and Hydrogen Bonding

Effect of Hydrogen Bonding on the Pyramidalization of the Amino Group: Structure of 3,4-diaminobenzamidinium Chloride

Structure and Energetics of Complexes of B₁₂N₁₂ with Hydrogen Halides—SAPT(DFT) and MP2 Study

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Rehybridization as a general mechanism for maximizing chemical and supramolecular bonding and a driving force for chemical reactions

Cited by 77 publications

References 179 publications

tert-Butyl Carbocation in Condensed Phases: Stabilization via Hyperconjugation, Polarization, and Hydrogen Bonding

tert-Butyl Carbocation in Condensed Phases: Stabilization via Hyperconjugation, Polarization, and Hydrogen Bonding

Effect of Hydrogen Bonding on the Pyramidalization of the Amino Group: Structure of 3,4-diaminobenzamidinium Chloride

Structure and Energetics of Complexes of B12N12 with Hydrogen Halides—SAPT(DFT) and MP2 Study

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Structure and Energetics of Complexes of B₁₂N₁₂ with Hydrogen Halides—SAPT(DFT) and MP2 Study