The Anti-Hydrogen Bond in Aromatic<i>N</i>-Sulfinylamines with Ortho H Atoms

Muchall, Heidi M.

doi:10.1021/jp002984k

Cited by 38 publications

(32 citation statements)

References 27 publications

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“…Interaction with one water molecule is the simplest model in the study of the hydrolysis of N-sulfinylaniline (1). Even though the formation of a prereaction complex usually precedes the reaction, we were only able to locate complex 2a with water situated on top of the S=O bond (Fig.…”

Section: Reaction Of N-sulfinylaniline With One Water Moleculementioning

confidence: 94%

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Influence of the number of water molecules on the mechanism of N-sulfinylaniline hydrolysis

Ivanova¹,

Muchall²

2005

Can. J. Chem.

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The mechanism of the uncatalyzed hydrolysis of N-sulfinylaniline (Ph-N=S=O) has been studied with B3LYP/6-31+G(2d,2p) in the gas phase, with explicit treatment of water molecules. Hydrolysis involves water attack on sulfur, with a close to perpendicular alignment of a water molecule and the NSO plane in both prereaction complexes and transition states for the rate-determining step. Consequently, the distance of the weak S···O interaction, together with the efficiency of protonation of either nitrogen (attack across the N=S bond) or oxygen (attack across the S=O bond) atoms of the NSO group, determines the height of the activation barrier for hydrolysis. While the reaction with one water molecule is characterized by an unreasonably high enthalpy of activation, a cooperative effect from the weak interactions appears with the inclusion of a second water molecule, where both participate in the reaction, and the activation enthalpy drops significantly. The preference for attack across the S=O bond that is found in the reaction with one water molecule switches to a dominance of attack across the N=S bond in the reaction with three water molecules.Résumé : Faisant appel à des calculs théoriques au niveau B3LYP/6-31+G(2d,2p), on a étudié le mécanisme de l'hydrolyse non catalysée du N-sulfinylaniline (Ph-N=S=O) en phase gazeuse, en faisant un traitement explicite des molécules d'eau. Dans l'étape cinétiquement déterminante, l'hydrolyse implique une attaque de l'eau sur le soufre, avec un alignement pratiquement perpendiculaire d'une molécule d'eau et du plan NSO tant dans les complexes préréaction-nels que dans les états de transition. En conséquence, la distance de la faible interaction S···O ainsi que l'efficacité de la protonation de l'atome d'azote (attaque à travers la liaison N=S) ou de l'atome d'oxygène (attaque à travers la liaison S=O) du groupe NSO détermine la hauteur de la barrière d'activation de l'hydrolyse. Alors que la réaction avec une molécule d'eau est caractérisée par une enthalpie d'activation anormalement élevée, il semble se développer un effet de synergie avec les interactions faibles lors de l'inclusion d'une deuxième molécule d'eau alors que les deux participent à la réaction et que l'enthalpie d'activation diminue d'une façon significative. La préférence pour l'attaque à travers la liaison S=O qui caractérise la réaction avec une molécule d'eau se déplace vers une dominance pour une attaque à travers la liaison N=S dans la réaction avec trois molécules d'eau.

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Section: Reaction Of N-sulfinylaniline With One Water Moleculementioning

confidence: 94%

“…Our interest in the electronic and molecular structures of NSO species (1,2) is closely related to their reactivity. NSulfinylamines (R-N=S=O) were first prepared by Michaelis in 1890 (3) and their reaction with water was one of the first properties to be observed experimentally.…”

Section: Introductionmentioning

confidence: 99%

Influence of the number of water molecules on the mechanism of N-sulfinylaniline hydrolysis

Ivanova¹,

Muchall²

2005

Can. J. Chem.

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“…From a simplistic model, a red shift would be the expected effect as far as the D-HÁ Á ÁA interaction increases the D-H bond length. Blue shift has been described in C-HÁ Á ÁO, C-HÁ Á Áp and N-HÁ Á ÁO systems [34][35][36]. The explanations advanced for the blue shift effect were reviewed by Alabugin et al [37].…”

Section: H-bonding Manifestation From Calculated Vibrational Spectramentioning

confidence: 99%

Conformational study of isolated pindolol by HF, DFT and MP2 calculations

Nunes

Jesus

Rosado

et al. 2007

Journal of Molecular Structure: THEOCHEM

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In the present work a conformational analysis of pindolol, a beta-blocker, is performed using several computational methods, including HF, DFT (B3LYP) and MP2. The relative electronic energies as well as the relevant dihedral angles of the significant conformer geometries are reported.At the HF and DFT levels the most stable conformers of pindolol are characterized by an extended backbone structure, minimizing the steric repulsions between the indole ring and the side chain. The two backbone dihedrals, defining the position of the ring relatively to the side chain, are found to be particularly important. The lower energy structures obtained by HF and DFT also contribute significantly to the MP2 conformational population. This last method increases the stability of some conformers presenting a more folded backbone.Most conformers exhibit hydrogen bonding. This feature, although not being the dominant factor in energetic terms, appears to be of foremost importance to define the geometry of the molecule. Four intramolecular hydrogen bonds established between the polar groups were identified by the structural geometric parameters. These involved the hydroxyl and amine functional groups and were identified and characterized by the frequency shift in their stretching vibration modes.

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“…However, calculations reported for the parent sulfinylaniline 11 and some others substituted sulfinylanilines [3][4][5] demonstrate that only the syn form is observed in liquid phase. 7 The same was also evidenced now as a consequence of the orbital interaction of oxygen lone pairs towards the σ* (C6-H1) orbital in the syn form (these interactions are absent in the anti configuration). In order to describe the conformational properties of the o-fluorosulfinylaniline, the potential energy function for rotation around the N=S bond was determined by structure optimizations at fixed dihedral angles C-N=S=O in steps of 30°.…”

Section: Quantum Chemical Calculations Analysismentioning

confidence: 68%

“…It is known that the N=S bond is a four electron bond with the S atom as the positive and the N atom as the negative end of the dipole while the SO bond has been described as S + -O -. 7 By using 1 H and 17 O NMR spectroscopies, experimental evidence for this C-H⋅⋅⋅O interaction was put forward. 5 Glass et al confirmed that the -N=S=O group is electron withdrawing in p-disubstituted benzenes, withdrawing electrons from the benzene ring.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of o-fluorosulfinylaniline. A comparative vibrational study of fluorinated sulfinylaniline series

2015

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ARTICLE This journal isThe synthesis of o-fluorosulfinylaniline is reported with the aim to complete the fluorinated sulfinylanilines series. The FT-IR and Raman spectra of o-fluorosulfinylaniline are recorded and the fundamental modes of its vibrational frequencies are assigned together with a tentative assignment of the NMR and mass spectra. Quantum chemical calculations on the optimized geometry predict in the liquid phase a planar structure with syn orientation of the -N=S=O moiety (syn of the S=O double bond relative to the C-N single bond), which belongs to C S symmetry group. The experimentally observed spectral data (FT-IR, Raman, 1 H and 13 C and GC-Mass Spectrometry) of the title compound are compared with those obtained theoretically from DFT calculations and gauge including atomic orbital (GIAO) method. Vibrational frequencies were assigned with the aid of anharmonic variational methods (VSCF) obtaining a significantly better agreement with experiment than with simple harmonic oscillator methods. Moreover, stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using Natural Bond Orbital (NBO) analysis. ARTICLEThis journal is

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The Anti-Hydrogen Bond in AromaticN-Sulfinylamines with Ortho H Atoms

Cited by 38 publications

References 27 publications

Influence of the number of water molecules on the mechanism of N-sulfinylaniline hydrolysis

Influence of the number of water molecules on the mechanism of N-sulfinylaniline hydrolysis

Conformational study of isolated pindolol by HF, DFT and MP2 calculations

Synthesis and characterization of o-fluorosulfinylaniline. A comparative vibrational study of fluorinated sulfinylaniline series

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