Dative behavior of N-heterocyclic carbenes (NHCs) with selenium in Se-NHC compounds

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Munazzah Yaqoob ◽  
Mahvish Abbasi ◽  
Hira Anwar ◽  
Javed Iqbal ◽  
Mohammad Asad ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Carbon Atom ◽  
Lone Pair ◽  
Heterocyclic Ring ◽  
Heterocyclic Carbenes ◽  
The Other ◽  
Donor Ligands ◽  
Important Research ◽  
Dative Bond ◽  
Back Bonding

Abstract N-heterocyclic carbenes (NHCs) are an eminent class of carbenes having a heterocyclic ring in which a divalent carbon atom is attached directly to a nitrogen atom. In the NHCs, the donation of lone pair is another important research in the dative bonding and not only in NHCs the dative bond plays a functionalized role in the other classes of complex formation like ylidones L → E ← L and carbones L → C ← L. M–NHC bond is L-M sigma-dative bond and NHCs are considered as strong sigma-donor ligands. The clear picture of the M–NHC bond can be better understood by M–NHC pi-interaction. M-L pi interaction is comprised of two steps. One is L → M sigma-donation and M → L π* back bonding. This dative donor nature of NHC and also its behavior in organoselenium is studied through DFT in which it’s optimized structure, bond lengths, molecular vibrations are calculated.

Alkylation by secondary alcohols. I. The reaction of xanthydrol with some N1-monosubstituted sulfanilamides and related compounds

1967 ◽  
Vol 45 (13) ◽  
pp. 1411-1424 ◽  
Author(s):  
R. E. Moskalyk ◽  
L. G. Chatten
Keyword(s):  
Nitrogen Atom ◽  
Tautomeric Form ◽  
Heterocyclic Ring ◽  
The Other ◽  
Secondary Alcohols ◽  
Amino Group ◽  
Aromatic Character ◽  
Carbonium Ion ◽  
Other Hand ◽  
Related Compounds

Sulfanilamides were found to undergo alkylation with xanthydrol, yielding either mono- or di-xanthenyl derivatives. The site of substitution, common to all sulfanilamides having a free p-amino group, was shown to be the N4-position in the sulfanilamide molecule. Three additional unique reactive sites were observed. Sulfanilamides carrying a thiazole, thiadiazole, or pyridazine substituent in the N1-position were also alkylated on the annular nitrogen atom of the heterocyclic ring, the reaction having occurred from the imido tautomeric form. Sulfisoxazole (IK), on the other hand, reacted from the amido form to give the N1,N4-dixanthenyl derivative. Sulfadimethoxine (Ih) was substituted at carbon, as well as at nitrogen, to yield N4-xanthenyl-N1-(2,6-dimethoxy-5-(9-xanthenyl)-4-pyrimidyl)sulfanilamide.Sulfanilamides possessing pKa values of about 5.5 were found to be sufficiently acidic to catalyze their own reaction with xanthydrol, and no external catalyst was necessary. The exceptional ease of formation of the xanthylium ion was postulated to be associated with the resulting stability of this carbonium ion by virtue of its acquired aromatic character.

Preparation and 31P NMR characterization of N-bonded complexes of platinum(II) with a phosphadithiatriazine: X-ray structure of trans-PtCl2(Pet3)(η1-N-Ph2PS2N3)

1992 ◽  
Vol 70 (10) ◽  
pp. 2602-2606 ◽  
Author(s):  
Tristram Chivers ◽  
Robert W. Hilts ◽  
Ian H. Krouse ◽  
A. Wallace Cordes ◽  
Randal Hallford ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Free Ligand ◽  
Heterocyclic Ring ◽  
Structural Features ◽  
The Other ◽  
Monoclinic Space Group ◽  
Hydrogen Atoms ◽  
Absorption Bands ◽  
X Ray ◽  
Nmr Characterization

The reaction of Ph2PS2N3 with [Pt2(μ-Cl)2(PEt3)4][BF4]2 or [PtCl2(PEt3)]2, in dichloromethane at 23° C produces the 1:1 adducts cis-[PtCl(PEt3)2(Ph2PS2N3)][BF4], 3, and trans-[PtCl2(PEt3)(Ph2PS3N2)], 4, respectively, in good yields. The 31P NMR data for 3 and 4 indicate that (i) the platinum is attached to a nitrogen atom adjacent to phosphorus in both these adducts, (ii) the PEt3 ligands in 3 are in mutually cis positions, and (iii) the PEt3 ligand in 4 is trans to the heterocyclic nitrogen. These structural features were confirmed by an X-ray analysis of 4. Crystals of 4 are monoclinic, space group P21/c, with a = 14.920(3) Å, b = 8.966(5) Å, c = 19.103(5) Å, β = 109.32(2)°, V = 2411.6(16) Å3, and Z = 4. The least-squares refinement with anisotropic thermal parameters for all non-hydrogen atoms converged at R = 0.050 and Rw = 0.053. The Pt—N bond length is 2.122(15) Å and the coordinated nitrogen atom is lifted ca. 0.63(2) Å out of the plane containing the other heterocyclic ring atoms. The attachment of a platinum(II) centre to the PN3S2 ring perturbs the S—N bond lengths significantly. The S—N distance involving the coordinated nitrogen is 1.672(16) Å, while the other S—N distances are 1.631(19), 1.555(19), and 1.562(19) Å, indicative of a localized sulfur diimide (-N=S=N-) structure. The UV–visible spectra of 3 and 4 in CH2Cl2 exhibit absorption bands at 514 and 528 nm, respectively, but dissociation of these adducts to give the free ligand Ph2PS2N3 occurs readily in dilute solution.

Structure and bonding in cyclic phosphoramidates as determined by carbon-13 magnetic resonance

1979 ◽  
Vol 57 (1) ◽  
pp. 21-26 ◽  
Author(s):  
Gerald W. Buchanan ◽  
Frederick G. Morin
Keyword(s):  
Magnetic Resonance ◽  
Nitrogen Atom ◽  
Electron Pair ◽  
Chemical Shifts ◽  
Lone Pair ◽  
Ring Conformation ◽  
Delocalized Electron ◽  
Nitrogen Lone Pair ◽  
Structure And Bonding

13C chemical shifts and 13C–31P couplings are reported for 11 cyclic phosphoramidates of ring sizes from four to nine. Vicinal couplings are compared with those of carbocyclic analogs and provide insight regarding the degree of nitrogen lone pair derealization into the N—P bond. For six-membered and larger rings, there appears to be nearly complete lone pair delocalization, i.e., a trigonal planar nitrogen atom. In azetidine derivatives the nitrogen lone pair remains localized, giving rise to a highly puckered ring conformation. Pyrrolidine derivatives are viewed as having a nitrogen with a partially delocalized electron pair.

Nucleophile/Electrophile Combinations in Aromatic Substitution: From Wheland to Wheland–Meisenheimer Intermediates Using Strongly Activated Arenes

Synthesis ◽  
2017 ◽  
Vol 49 (15) ◽  
pp. 3347-3356 ◽  
Author(s):  
Gabriele Micheletti ◽  
Carla Boga
Keyword(s):  
Nitrogen Atom ◽  
Carbon Atom ◽  
Short Review ◽  
Alkyl Halides ◽  
Aryl Halides ◽  
Aromatic Substitution ◽  
Aromatic Carbon ◽  
Isolation And Characterization ◽  
Acyl Halides

This short review provides an overview on the interaction between 1,3,5-triaminobenzene derivatives and different kinds of electrophiles. Due to the ambident reactivity of these nucleophiles (i.e., at the nitrogen atom of the substituents and at the aromatic carbon atom) different compounds can be obtained. Particular attention is devoted to the detection, isolation, and characterization of covalent intermediates of aromatic substitution, starting from Wheland intermediates until the first detection and characterization of Wheland–Meisenheimer intermediates.1 Introduction2 Reactions between 1,3,5-Triaminobenzene Derivatives and Charged Electrophiles2.1 The Proton as an Electrophile2.2 Arenediazonium Salts as Electrophiles3 Reactions between 1,3,5-Triaminobenzene Derivatives and Neutral­ Electrophiles3.1 Alkyl Halides as Electrophiles3.2 Acyl Halides and Sulfonyl Chlorides as Electrophiles3.3 Aryl Halides and Heteroaryl Halides as Electrophiles3.4 Polynitroheteroaromatics as Electrophiles4 Conclusion

Abnormal C5-Bound N-Heterocyclic Carbenes:  Extremely Strong Electron Donor Ligands and Their Iridium(I) and Iridium(III) Complexes

2004 ◽  
Vol 23 (10) ◽  
pp. 2461-2468 ◽  
Author(s):  
Anthony R. Chianese ◽  
Anes Kovacevic ◽  
Brian M. Zeglis ◽  
J. W. Faller ◽  
Robert H. Crabtree
Keyword(s):  
Electron Donor ◽  
Heterocyclic Carbenes ◽  
Donor Ligands ◽  
Strong Electron

scholarly journals Synthesis and Biological Activities of Some Pyrimidine Derivatives: A Review

2020 ◽  
Vol 36 (6) ◽  
pp. 1001-1015
Author(s):  
Nadia Ali Ahmed Elkanzi
Keyword(s):  
Nitrogen Atom ◽  
Medicinal Chemistry ◽  
Biological Activities ◽  
Heterocyclic Ring ◽  
Ring System ◽  
Pyrimidine Derivatives ◽  
Pharmacological Activities ◽  
Cardiovascular Agents ◽  
Anti Hiv ◽  
Biological And Pharmacological Activities

Nitrogen containing synthetically and biologically important heterocyclic ring system namely pyrimidine possess both biological and pharmacological activities, and defend as aromatic six heterocyclic with 1and 3 nitrogen atom in ring. Preparation of pyrimidine via different methods offer its importance in fields of medicinal chemistry and Chemistry. Pyrimidines and their derivatives act as anti-inflammatory, anti-malaria, anti-tumor, cardiovascular agents, anti-neoplastic, anti-tubercular, anti- HIV, diuretic ,anti-viral, anti-microbial, ,analgesic .This review give light up on biological and pharmacological activities of pyrimidine nucleus.

Protein environment affects the water–tryptophan binding mode. MD, QM/MM, and NMR studies of engrailed homeodomain mutants

2018 ◽  
Vol 20 (18) ◽  
pp. 12664-12677 ◽  
Author(s):  
Nad'a Špačková ◽  
Zuzana Trošanová ◽  
Filip Šebesta ◽  
Séverine Jansen ◽  
Jaroslav V. Burda ◽  
...  
Keyword(s):  
Amino Acids ◽  
Lone Pair ◽  
Binding Mode ◽  
The Other ◽  
Water Molecules ◽  
Interaction Type ◽  
Nmr Studies ◽  
Engrailed Homeodomain ◽  
The One ◽  
Protein Environment

Water molecules can interact with the π-face of tryptophan either forming an O–H⋯π hydrogen bond or by a lone-pair⋯π interaction. Surrounding amino acids can favor the one or the other interaction type.

P-doped graphene-C60 nanocomposite: A donor–acceptor complex with a P-C dative bond

2022 ◽  
Author(s):  
Rabindranath Lo ◽  
Debashree Manna ◽  
Pavel Hobza
Keyword(s):  
Electron Acceptor ◽  
The Other ◽  
Acceptor Complex ◽  
Dative Bond ◽  
Other Hand ◽  
Doped Graphene ◽  
Donor Acceptor

Phosphorous-doped graphene can form a covalent dative bond with the electron acceptor, C60 molecule. On the other hand, C60 on graphene and N-doped graphene surfaces can only form vdW complexes....

Die Kristallstruktur des Lithium-Benzamidinats {Li3[C6H5 - C(NSiMe3)2]3 · NC - C6H5} / The Crystal Structure of the Lithium Phenylamidinate {Li3[C6H5 - C(NSiMe3)2]3 · NC - C6H5}

1994 ◽  
Vol 49 (10) ◽  
pp. 1444-1447 ◽  
Author(s):  
Helmut Goesmann ◽  
Dieter Fenske
Keyword(s):  
Crystal Structure ◽  
Nitrogen Atom ◽  
Single Crystals ◽  
Title Compound ◽  
The Other ◽  
Space Group ◽  
Structure Solution

AbstractSingle crystals of the title compound have been prepared by the reaction of benzonitrile with LiN-(SiMe3)2 in hexane and subsequent evaporation of the solvent. Space group P21/n, Z = 4, structure solution with 7945 observed unique reflections. R = 0.052. Lattice dimensions at -70 °C: a = 1485.2(9); b = 2486.9(11); c = 1568.9(8) pm; β = 91.06(4)°. The compound forms a trimeric ion ensemble in which two of the lithium cations are coordinated by three nitrogen atoms of two phenylamidinate an ions, the other one by four nitrogen atoms of two chelating phenylaminidate anions and in addition by the nitrogen atom of a benzonitrile molecule.

Theoretical Investigation of Main-Group Element Hydride Insertion into Phosphorus-Heterocyclic Carbenes (PHCs)

2020 ◽  
Vol 73 (8) ◽  
pp. 787
Author(s):  
Khalidah H. M. Al Furaiji ◽  
Andrew Molino ◽  
Jason L. Dutton ◽  
David J. D. Wilson
Keyword(s):  
Computational Study ◽  
Ring Expansion ◽  
Heterocyclic Ring ◽  
Main Group ◽  
Heterocyclic Carbenes ◽  
Group Element ◽  
Steric Effects ◽  
Main Group Element ◽  
Theoretical Investigations ◽  
Electronic And Steric Effects

Initial reports of ring expansion reactions (RER) of N-heterocyclic carbenes (NHCs) with main-group element hydrides have led to several synthetic and theoretical investigations, which include reports of insertion by Be, B, Al, Si, and Zn hydrides. The RERs generally lead to insertion of the heteroatom into the endocyclic C–N bond with formation of an expanded heterocyclic ring. Following the recent isolation of a P-heterocyclic carbene (PHC), here we report results from a computational study (RI-SCS-MP2/def2-TZVP//M06–2X/def2-TZVP) of RERs with a series of PHCs for the ring-insertion of silicon (SiH4, SiH2Ph2) and boron (BH3, BH2NMe2) hydrides. In order to explore the roles of both electronic and steric effects on PHCs and their reactivity, a series of P-substituent PHCR (R=H, Me, Ph, and bulky Ar groups) were investigated. Bulky R groups serve to maximise ring planarity and the σ-donating capability of the PHC. For RER, the PHC analogues exhibit facile initial hydride transfer from the main-group hydrides to the carbene carbon, with barriers that are substantially lower than with NHCs. However, the full ring insertion mechanisms for PHCs are, in general, kinetically unfavourable due to a large barrier associated with the ring-expansion step. While bulky P-substituents maximise heterocycle planarity towards that of NHCs, the RER reactivity with bulky PHCs does not reflect that of an NHC.

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