Naming Interactions from the Electrophilic Site

2014 ◽  
Vol 14 (6) ◽  
pp. 2697-2702 ◽  
Author(s):  
Gabriella Cavallo ◽  
Pierangelo Metrangolo ◽  
Tullio Pilati ◽  
Giuseppe Resnati ◽  
Giancarlo Terraneo
Keyword(s):  
Electrophilic Site

Reactions of the super-electrophile, 2-(2′,4′-dinitrophenyl)-4,6-dinitrobenzotriazole 1-oxide, with methoxide and tert-butoxide: basicity and steric hindrance as factors in σ-complex formation versus nucleophilic displacement

1991 ◽  
Vol 69 (6) ◽  
pp. 978-986 ◽  
Author(s):  
Julian M. Dust ◽  
Erwin Buncel
Keyword(s):  
Steric Hindrance ◽  
Adduct Formation ◽  
Reaction Pathways ◽  
Resonance Spectroscopy ◽  
Aromatic Nucleophilic Substitution ◽  
Rapid Decomposition ◽  
Nucleophilic Displacement ◽  
Energy Reaction ◽  
Electrophilic Site ◽  
Relative Electrophilicity

The course of the reactions of methoxide and tert-butoxide with 2-(2′,4′-dinitrophenyl)-4,6-dinitrobenzotriazole 1-oxide (4) clearly shows that the C-7 electrophilic site is significantly more reactive than the C-1′ site of the substrate. The reaction pathways of these alkoxides, which differ in basicity (as a measure of nucleophilicity) and steric bulk, were followed by 400 MHz 1H nuclear magnetic resonance spectroscopy. While both alkoxides lead to immediate formation of the respective C-7 anionic σ-adducts, a greater percentage of C-7 adduct formation occurs with methoxide as attacking nucleophile. Reaction with excess alkoxide results in attack at C-1′ being observed, as well. This leads to formation of metastable C-1′ σ-adducts, whose rapid decomposition results in formation of 2,4-dinitrophenyl ethers and the dinitrobenzotriazole 1-oxyanion in an overall nucleophilic displacement reaction. Under these excess conditions, methoxide also causes a faster rate of displacement than does tert-butoxide as nucleophile. These results are discussed on the basis of the basicity of the nucleophiles, the relative electrophilicity of the positions in the substrate (C-7 versus C-1′), the steric hindrance involved in attack and in the resultant C-7 and C-1′ complexes, and in terms of an activation energy/reaction coordinate profile comparing the pathways for attack at the two electrophilic sites. Key words: anionic σ-complexes, super-electrophiles, aromatic nucleophilic substitution (SN Ar).

Silver ion binding to the organophosphorus pesticide diazinon and hydrolytic pathways revealed by mass spectrometric and NMR studies

2015 ◽  
Vol 93 (11) ◽  
pp. 1266-1275 ◽  
Author(s):  
Martin Wyer ◽  
Gary W. vanLoon ◽  
Julian M. Dust ◽  
Erwin Buncel
Keyword(s):  
Mass Spectrometry ◽  
Organophosphorus Pesticide ◽  
Lewis Base ◽  
Ionization Mass ◽  
Nmr Studies ◽  
Energy Profiles ◽  
Leaving Group ◽  
Bidentate Chelate ◽  
Hydrolysis Of ◽  
Electrophilic Site

This paper describes the first study of the interactions of Ag+ with the organophosphorus (OP) insecticide diazinon, 1. Electrospray ionization mass spectrometry (ESI-MS) with corroborative collision-induced dissociation-mass spectrometry (CID-MS) demonstrates that 1 forms a bidentate chelate with Ag+. The hydrolysis products of 1, the pyrimidinol (PY) and O,O-diethylphosphorothioic acid (PA), are also found to bind to Ag+ via N (PY) and S (PA) Lewis base sites, respectively. 31P and 1H nuclear magnetic resonance (NMR) spectra in solution, followed over time with varying ratios of Ag+ to 1, confirm the MS evidence and show Ag+ catalysis of hydrolysis (e.g., complete hydrolysis of 1 in ∼5 min (first-order half-life = 3 × 10−4 d; kobs = 2 × 103 d−1)) with equimolar Ag+; this represents an approximate 150 000-fold enhancement in hydrolysis with Ag+ as compared to its absence. A mechanism for the enhanced hydrolysis is proposed in which bidentate binding of Ag+ to S of the P=S electrophilic site in tandem with binding to N of the leaving group stabilizes the SN2(P) transition state relative to the ground state; this effect is described by qualitative energy profiles.

Oligonucleotide Conjugates Derived from an Electrophilic Site: Conjugation to Baseless Carbohydrate Residue. Synthesis, Hybridization and Modeling Studies

1997 ◽  
Vol 16 (7-9) ◽  
pp. 1741-1744 ◽  
Author(s):  
Muthiah Manoharan ◽  
Laura K. Andrade ◽  
Venkatraman Mohan ◽  
Susan M. Freier ◽  
P. Dan Cook
Keyword(s):  
Carbohydrate Residue ◽  
Modeling Studies ◽  
Oligonucleotide Conjugates ◽  
Electrophilic Site

Carbon versus oxygen nucleophilic selectivity in the reaction of the aryloxide ions, 2,6- and 3,5-di-tert-butylphenoxide, with the 2-[(nitro)\dn6 xaryl]-4,6-dinitrobenzotriazole 1-oxide series of super-electrophiles. Stereoelectronic factors on C-7 Meisenheimer complex formation versus C-1' SNAr displacement

1998 ◽  
Vol 76 (6) ◽  
pp. 662-671 ◽  
Author(s):  
Julian M Dust ◽  
Richard A Manderville
Keyword(s):  
Nmr Spectroscopy ◽  
Nucleophilic Aromatic Substitution ◽  
Nucleophilic Attack ◽  
Aromatic Substitution ◽  
Factors Affecting ◽  
H Nmr ◽  
Sterically Demanding ◽  
Biphenyl Derivative ◽  
First Time ◽  
Electrophilic Site

The 2-[(nitro)xaryl]-4,6-dinitrobenzotriazole 1-oxides (1, Pi-DNBT (x = 3); 2, DNP-DNBT (x = 2); 3, NP-DNBT (x = 1)) are electron-deficient nitro-substituted heteroaromatic substrates that possess two sites for nucleophilic attachment: C-7 and C-1'. Generally, attack at the super-electrophilic C-7 site yields spectroscopically observable anionic sigma -bonded adducts, whereas attack at C-1' leads to displacement products in an overall process of nucleophilic aromatic substitution (SNAr). To gain an understanding of the factors affecting C-1' versus C-7 attack by potentially ambident aryloxide (C- and O-)nucleophiles, we have monitored the reactions of 1-3 with 2,6-di-tert-butylphenoxide (2,6-ArO-) and 3,5-di-tert-butylphenoxide (3,5-ArO-) using 400 MHz 1H NMR spectroscopy (deuterated dimethyl sulfoxide solvent at ambient temperature). The results indicate that 2,6-ArO- acts only as a C-nucleophile with O-attack precluded, presumably by the sterically demanding tert-butyl groups flanking the O-nucleophilic centre. Although 2,6-ArO- reacts preferentially at C-7 of 1-3, the biphenyl derivative that arises from C-1' attack is also observed with 1, the first time that C-nucleophilic attack has been seen at this electrophilic site. In contrast, 3,5-ArO- acts only as an O-nucleophile, also as a consequence of the steric hindrance to the C-4 position; this aryloxide reacts entirely at C-1' of Pi-DNBT but also exclusively at C-7 of 3. However, with DNP-DNBT, 2, both the C-7 O-adduct and C-1' displacement products are noted; attack at C-1' is dominant. The selectivity (C-7 versus C-1') found in these reactions is discussed with emphasis given to stereoelectronic factors that may stabilize the putative C-1' O-adducts.Key words: aryloxides, super-electrophiles, Meisenheimer complexes, 2-[(nitro)xaryl]-4,6-dinitrobenzotriazole 1-oxides.

Ketone Derivatives of Poly(Methylphenylphosphazene):  Incorporation of an Electrophilic Site into Poly(Alkyl/Arylphosphazenes)

1998 ◽  
Vol 31 (25) ◽  
pp. 9084-9086 ◽  
Author(s):  
Patty Wisian-Neilson ◽  
Cuiping Zhang
Keyword(s):  
Derivatives Of ◽  
Electrophilic Site

scholarly journals Identification of the Tetrel Bonds between Halide Anions and Carbon Atom of Methyl Groups Using Electronic Criterion

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1083 ◽  
Author(s):  
Ekaterina Bartashevich ◽  
Yury Matveychuk ◽  
Vladimir Tsirelson
Keyword(s):  
Binding Energy ◽  
Carbon Atom ◽  
Molecular Complexes ◽  
Electron Donors ◽  
Methyl Groups ◽  
Geometrical Parameters ◽  
Halide Anion ◽  
Methyl Group ◽  
Electrophilic Site ◽  
Tetrel Bonds

The consideration of the disposition of minima of electron density and electrostatic potential along the line between non-covalently bound atoms in systems with Hal−···CH3–Y (Hal− = Cl, Br; Y = N, O) fragments allowed to prove that the carbon atom in methyl group serves as an electrophilic site provider. These interactions between halide anion and carbon in methyl group can be categorized as the typical tetrel bonds. Statistics of geometrical parameters for such tetrel bonds in CSD is analyzed. It is established that the binding energy in molecular complexes with tetrel bonds correlate with the potential acting on an electron in molecule (PAEM). The PAEM barriers for tetrel bonds show a similar behavior for both sets of complexes with Br− and Cl− electron donors.

scholarly journals Definition of the chalcogen bond (IUPAC Recommendations 2019)

2019 ◽  
Vol 91 (11) ◽  
pp. 1889-1892 ◽  
Author(s):  
Christer B. Aakeroy ◽  
David L. Bryce ◽  
Gautam R. Desiraju ◽  
Antonio Frontera ◽  
Anthony C. Legon ◽  
...  
Keyword(s):  
Intramolecular Interactions ◽  
Chalcogen Bond ◽  
Specific Subset ◽  
Group 16 ◽  
Definition Of ◽  
Electrophilic Site

Abstract This recommendation proposes a definition for the term “chalcogen bond”; it is recommended the term is used to designate the specific subset of inter- and intramolecular interactions formed by chalcogen atoms wherein the Group 16 element is the electrophilic site.

Electronic criterion for categorizing the chalcogen and halogen bonds: sulfur–iodine interactions in crystals

2019 ◽  
Vol 75 (2) ◽  
pp. 117-126 ◽  
Author(s):  
Ekaterina Bartashevich ◽  
Svetlana Mukhitdinova ◽  
Irina Yushina ◽  
Vladimir Tsirelson
Keyword(s):  
Electrostatic Potential ◽  
Noncovalent Interactions ◽  
Molecular Crystals ◽  
Mutual Orientation ◽  
Halogen Bonds ◽  
Covalent Bonds ◽  
Interatomic Distances ◽  
Different Types ◽  
Electrophilic Site ◽  
Selection Of

Diversity of mutual orientations of Y–S and I–X and covalent bonds in molecular crystals complicate categorizing noncovalent chalcogen and halogen bonds. Here, the different types of S...I interactions with short interatomic distances are analysed. The selection of S...I interactions for the categorization of the chalcogen and halogen bonds has been made using angles that determine the mutual orientation of electron lone pairs and σ-holes interacted S and I atoms. In complicated cases of noncovalent interactions with `hole-to-hole' of S and I orientations, distinguishing the chalcogen and halogen bonds is only possible if the atom is uniquely determined, which also provides the electrophilic site. The electronic criterion for chalcogen/halogen bonds categorizing that is based on analysis of dispositions of electron density and electrostatic potential minima along the interatomic lines has been suggested and its effectiveness has been demonstrated.

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