Basicité de liaison hydrogène de formamidines substituées sur l'azote imino

1992 ◽  
Vol 70 (8) ◽  
pp. 2203-2208 ◽  
Author(s):  
Ewa D. Raczyńska ◽  
Christian Laurence ◽  
Michel Berthelot
Keyword(s):  
Hydrogen Bonding ◽  
Nitrogen Atom ◽  
Hydrogen Bonds ◽  
Frequency Shift ◽  
Field Effect ◽  
Formation Constant ◽  
Steric Effect ◽  
Imino Nitrogen ◽  
Alkyl Groups ◽  
Electron Withdrawing Substituents

The basicity of the hydrogen bonds of formamidines 1–19 was measured by means of the formation constant KHB of their complexes with p-fluorophenol and the frequency shift Δν(OH) of methanol hydrogen-bonded to 1–19. The study of the ν(C=N) band shows that hydrogen bonding takes place with the imino nitrogen atom. On the hydrogen-bonding basicity scale, the formamidines appear to be more basic than the corresponding amides and pyridines, and as basic as the imidazoles. The field effect of electron-withdrawing substituents and the steric effect of bulky alkyl groups on the imino nitrogen atom markedly decrease the hydrogen-bonding basicity.

Hydrogen Bonds and FTIR Peaks of Polyether Polyurethane-Urea

2019 ◽  
Vol 815 ◽  
pp. 151-156
Author(s):  
Xu Zhao ◽  
Yu Hong Qi ◽  
Ke Jiao Li ◽  
Zhan Ping Zhang
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Steric Effect ◽  
Electronic Effect ◽  
Theoretical Foundation ◽  
Microphase Separation ◽  
Ether Linkage ◽  
Proton Donors ◽  
Hard Segments ◽  
Degree Of Order

Various types of hydrogen bonds exist in polyether polyurethane, polyurethane-urea and polyurea (PUA) and can cause microphase separation. The morphology, properties and applications of polyether PUA are determined by the microphase separation. All kinds of hydrogen bonds make it difficult to assignments of Fourier transform infrared spectroscopy (FTIR) peaks of ether linkage, amine and carbonyl group. This affects the calculation of the hydrogen bonding degree of the hard segments for estimating the degree of microphase separation. This paper summarized hydrogen bonding structures between proton donors and proton acceptors. By analyzing the influence of electronic effect, steric effect, various types of hydrogen bonds and the degree of order of hydrogen bonding on infrared peaks, the relationships between hydrogen bonding structures and infrared peaks are established. Lay the theoretical foundation for evaluating the degree of microphase separation by FTIR method.

A New Hydrogen-Bonding Motif with Constituents Bearing Donor and Acceptor Sites 7 Å Apart

2005 ◽  
Vol 60 (7) ◽  
pp. 758-762 ◽  
Author(s):  
Katja Heinze ◽  
Anja Reinhart
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Nitrogen Atom ◽  
Hydrogen Bonds ◽  
Hydrogen Donor ◽  
Para Position ◽  
Hydrogen Acceptor ◽  
Aryl Ring ◽  
Donor And Acceptor ◽  
Pyrrole Nitrogen

Aryl substituted dipyrromethanes [di(pyrrol-2-yl)-phenyl-methanes] with hydrogen acceptor substituents R in para position of the aryl ring [R = CO2Me, CO2H, CONH(iPr) and NH2] located 7 Å apart from the hydrogen donor pyrrole nitrogen atom are shown to self-assemble in the solid state via hydrogen bonds to form rings or chains.

Structures of the adducts urea:pyrazine (1:1), thiourea:pyrazine (2:1) and thiourea:piperazine (2:1)

2017 ◽  
Vol 72 (6) ◽  
pp. 441-445 ◽  
Author(s):  
Cindy Döring ◽  
Julian F.D. Lueck ◽  
Peter G. Jones
Keyword(s):  
Hydrogen Bonding ◽  
Nitrogen Atom ◽  
Hydrogen Bonds ◽  
Layer Structure ◽  
Three Dimensional ◽  
Graph Set

AbstractThe adducts urea:pyrazine (1:1) (1), thiourea:pyrazine (2:1) (2), and thiourea:piperazine (2:1) (3) were prepared and their structures determined. Adduct 1 forms a layer structure, in which urea chains of graph set C(4)[${\rm{R}}_{\rm{2}}^{\rm{1}}$(6)] run parallel to the b axis and are crosslinked by N–H···N hydrogen bonding to the pyrazine residues. Adduct 2 is a variant of the well-known ${\rm{R}}_{\rm{2}}^{\rm{2}}$(8) ribbon substructure for urea/thiourea adducts, with the pyrazine molecules attached to the remaining thiourea NH groups via bifurcated hydrogen bonds (N–H···)2S; the more distant end of the pyrazine molecules is crosslinked to another symmetry-equivalent but perpendicular ribbon system, thus creating a three-dimensional packing. The packing of adduct 3 involves thiourea layers parallel to the ab plane; the piperazine molecules occupy the regions between these layers and are linked to the thiourea molecules by two hydrogen bonds (one as donor, one as acceptor) at each piperazine nitrogen atom.

scholarly journals Pyridine-4-carboxamidoxime N-oxide

IUCrData ◽  
2020 ◽  
Vol 5 (10) ◽  
Author(s):  
Clifford W. Padgett ◽  
Kirkland Sheriff ◽  
Will E. Lynch
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Nitrogen Atom ◽  
Hydrogen Bonds ◽  
Oxygen Atom ◽  
Metal Organic Frameworks ◽  
Amine Nitrogen Atom ◽  
Amine Nitrogen ◽  
Compound C ◽  
Metal Organic

Our work in the area of synthesis of metal–organic frameworks (MOFs) based on organic N-oxides led to the crystallization of pyridine-4-carboxamidoxime N-oxide. Herein we report the first crystal structure of the title compound, C6H7N3O2 [systematic name: (Z)-4-(N′-hydroxycarbamimidoyl)pyridine N-oxide]. The hydroxycarbamimidoyl group is essentially coplanar with the aromatic ring, r.m.s.d. = 0.112 Å. The compound crystallizes in hydrogen-bonding layers built from the formation of strong O—H...O hydrogen bonds between the oxime oxygen atom and the oxygen atom of the N-oxide, and the formation of N—H...O hydrogen bonds between one amine nitrogen atom and the N-oxide oxygen atom. These combined build R 3 4(24) ring motifs in the crystal. The crystal structure has no π–π interactions.

scholarly journals Diaquabis{μ-1,5-bis[(pyridin-2-yl)methylidene]carbonohydrazide(1–)}di-μ-chlorido-tetrachloridotetrazinc(II)

2020 ◽  
Vol 76 (8) ◽  
pp. 1349-1352
Author(s):  
Thierno Moussa Seck ◽  
Papa Aly Gaye ◽  
Cheikh Ndoye ◽  
Ibrahima Elhadji Thiam ◽  
Ousmane Diouf ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Hydrogen Bonds ◽  
Oxygen Atom ◽  
Basal Plane ◽  
Chloride Anion ◽  
Methanol Solution ◽  
Pyridine Nitrogen Atom ◽  
Imino Nitrogen ◽  
Pyridine Nitrogen ◽  
Dinuclear Unit

A tetranuclear ZnII complex, [Zn4(C13H11N6O)2Cl6(H2O)2] or {[Zn2(HL)(H2O)(Cl2)](μCl)2[Zn2(HL)(H2O)(Cl)]}2, was synthesized by mixing an equimolar amount of a methanol solution containing ZnCl2 and a methanol solution containing the ligand H2 L [1,5-bis(pyridin-2-ylmethylene)carbonohydrazide]. In the tetranuclear complex, each of the two ligand molecules forms a dinuclear unit that is connected to another dinuclear unit by two bridging chloride anions. In each dinuclear unit, one ZnII cation is pentacoordinated in a N2OCl2 in a distorted square-pyramidal geometry, while the other ZnII cation is hexacoordinated in a N3OCl2 environment with a distorted octahedral geometry. The basal plane around the pentacoordinated ZnII cation is formed by one chloride anion, one oxygen atom, one imino nitrogen atom and one pyridine nitrogen atom with the apical position occupied by a chloride anion. The basal plane of the hexacoordinated ZnII cation is formed by one chloride anion, one hydrazinyl nitrogen atom, one imino nitrogen atom and one pyridine nitrogen atom with the apical positions occupied by a water oxygen atom and a bridged chloro anion from another dinuclear unit, leading to a tetranuclear complex. A series of intramolecular C—H...Cl hydrogen bonds is observed in each tetranuclear unit. In the crystal, the tetranuclear units are connected by intermolecular C—H...Cl, C—H...O and N—H...O hydrogen bonds, forming a planar two-dimensional structure in the ac plane.

scholarly journals Hydrogen Bonds: Raman Spectroscopic Study

2021 ◽  
Vol 22 (10) ◽  
pp. 5380
Author(s):  
Boris A. Kolesov
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Spectroscopic Study ◽  
Raman Spectra ◽  
Temperature Region ◽  
Vibrational Frequency ◽  
Chemical Compounds ◽  
Raman Spectroscopic ◽  
Raman Spectroscopic Study ◽  
Proton Dynamics

The work outlines general ideas on how the frequency and the intensity of proton vibrations of X–H×××Y hydrogen bonding are formed as the bond evolves from weak to maximally strong bonding. For this purpose, the Raman spectra of different chemical compounds with moderate, strong, and extremely strong hydrogen bonds were obtained in the temperature region of 5 K–300 K. The dependence of the proton vibrational frequency is schematically presented as a function of the rigidity of O-H×××O bonding. The problems of proton dynamics on tautomeric O–H···O bonds are considered. A brief description of the N–H···O and C–H···Y hydrogen bonds is given.

2-Hydroxy-3-methoxybenzaldehyde (pyridinium-4-ylcarbonyl)hydrazone chloride hemihydrate

2006 ◽  
Vol 62 (5) ◽  
pp. o2043-o2044 ◽  
Author(s):  
Shao-Wen Chen ◽  
Han-Dong Yin ◽  
Da-Qi Wang ◽  
Xia Kong ◽  
Xiao-Fang Chen
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Compound C

The crystal structure of the title compound, C14H14ClN3O3 +·Cl−·0.5H2O, exhibits O—H...O, C—H...O, C—H...Cl, N—H...Cl and O—H...Cl hydrogen bonds. The chloride anions participate in extensive hydrogen bonding with the aminium cations and link molecules through multiple N—H+...Cl− interactions.

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