Heterocyclic Tautomerism. II. 4-Acylpyrazolones. X-Ray Crystal Structures of 4-Benzoyl-5-methyl-2-phenylpyrazol-3(2H)-one and 4-Acetoacetyl-3-methyl-1-phenylpyrazol-5-ol

1985 ◽  
Vol 38 (3) ◽  
pp. 401 ◽  
Author(s):  
MJ O'Connell ◽  
CG Ramsay ◽  
PJ Steel
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Room Temperature ◽  
Crystalline Form ◽  
Intermolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonds ◽  
X Ray ◽  
Intramolecular Hydrogen

The colourless crystalline form of the benzoylpyrazolone (2) has molecules with the NH structure (2c) stabilized by intermolecular hydrogen bonds. At room temperature crystals are monoclinic: P21/c, a 13.508(5), b 9.124(4), c 11.451(3)Ǻ, β 90.80(3)°, Z4; the structure was refined to R 0.059, Rw 0.048. The acetoacetylpyrazolone (3) has the OH structure (3c) with two intramolecular hydrogen bonds. At 193 K crystals are triclinic: Pī , a 7.142(2), b 13.704(8), c 14.699(7)Ǻ, α 117.36(3), β 96.87(3), γ 93.73(3)°, Z 4; the structure was refined to R 0.049, Rw 0.054.

Two phosphonodehydrotripeptides: Boc0–Gly1–Δ(Z)Phe2–α-Abu3PO3Me2and Boc0–Gly1–Δ(Z)Phe2–α-Nva3PO3Et2

2013 ◽  
Vol 69 (3) ◽  
pp. 277-281 ◽  
Author(s):  
Anna Brzuszkiewicz ◽  
Maciej Makowski ◽  
Marek Lisowski ◽  
Elżbieta Lis ◽  
Marta Otręba ◽  
...  
Keyword(s):  
Amino Acids ◽  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Main Chain ◽  
Intermolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonds ◽  
Crystal Forms ◽  
Intramolecular Hydrogen

The present paper reports the crystal structures of two short phosphonotripeptides (one in two crystal forms) containing one ΔPhe (dehydrophenylalanine) residue, namely dimethyl (3-{[tert-butoxycarbonylglycyl-α,β-(Z)-dehydrophenylalanyl]amino}propyl)phosphonate, Boc0–Gly1–Δ(Z)Phe2–α-Abu3PO3Me2, C21H32N3O7P, (I), and diethyl (4-{[tert-butoxycarbonylglycyl-α,β-(Z)-dehydrophenylalanyl]amino}butyl)phosphonate, Boc0–Gly1–Δ(Z)Phe2–α-Nva3PO3Et2, as the propan-2-ol monosolvate 0.122-hydrate, C24H38N3O7P·C3H8O·0.122H2O, (II), and the ethanol monosolvate 0.076-hydrate, C24H38N3O7P·C2H6O·0.076H2O, (III). The crystals of (II) and (III) are isomorphous but differ in the type of solvent. The phosphono group is linked directly to the last Cαatom in the main chain for all three peptides. All the amino acids aretranslinked in the main chains. The crystal structures exhibit no intramolecular hydrogen bonds and are stabilized by intermolecular hydrogen bonds only.

3,3′-N,N′-Bis(amino)-2,2′-bipyridine — An unusually methylation-resistant amine

2011 ◽  
Vol 89 (8) ◽  
pp. 971-977
Author(s):  
Danielle M. Chisholm ◽  
Robert McDonald ◽  
J. Scott McIndoe
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Complex Mixtures ◽  
Amino Groups ◽  
Intramolecular Hydrogen Bonds ◽  
X Ray ◽  
Intramolecular Hydrogen

Methylation of aromatic amino groups is usually straightforward, but the formation of two intramolecular hydrogen bonds in 3,3′-N,N′-bis(amino)-2,2′-bipyridine and (or) the potential for ring methylation prevents the clean tetramethylation of this molecule. Numerous attempts to make 3,3′-N,N′-bis(dimethylamino)-2,2′-bipyridine produced only complex mixtures of variously methylated products, and the only isolated molecule was 3,3′-N,N′-bis(methylamino)-2,2′-bipyridine, for which an X-ray crystal structure was obtained.

scholarly journals The Effects of the Solvents on the Macrocyclic Structures: From Rigid Pillararene to Flexible Crown Ether

2021 ◽  
Author(s):  
Shuangshuang Wang ◽  
Yanzhen Yin ◽  
Jian Gao ◽  
Xingtang Liang ◽  
Haixin Shi
Keyword(s):  
Hydrogen Bonds ◽  
Structural Design ◽  
Structural Features ◽  
Intermolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonds ◽  
Effect Of Solvents ◽  
Dynamics Simulations ◽  
Intramolecular Hydrogen ◽  
Macrocyclic Molecules ◽  
Polarity Of Solvents

The differences in the macrocyclic structures lead to different flexibilities, and yet the effect of solvents on the conformations is not clear so far. In this work, the conformations of four representational macrocyclic molecules (pillar[5]arene, p-tert-butyl calix[6]arene, benzylic amide macrocycle and dibenzo-18-crown-6) in three solvents with distinct polarity have been studied by all-atom molecular dynamics simulations. The structural features of the macrocycles in the solvents indicate that the conformations are related to the polarity of the solvents and the formation of hydrogen bonds. For the pillar[5]arene, the benzylic amide macrocycle and the dibenzo-18-crown-6, that cannot form intramolecular hydrogen bonds, the polarity of solvents is the major contributing factor in the conformations. The formation of intramolecular hydrogen bonds, in contrast, determinates the conformations of the calix[6]arene. Furthermore, the slight fluctuations of the structures will result in tremendous change of the intramolecular hydrogen bonds of the macrocycles and the intermolecular hydrogen bonds between the macrocycles and the solvents. The current theoretical studies that serve as a basis for the macrocyclic chemistry are valuable for the efficient structural design of the macrocyclic molecules.

N-(4-Methylbenzoyl)-N′-(4-methylphenyl)thiourea

2007 ◽  
Vol 63 (11) ◽  
pp. o4395-o4395
Author(s):  
S. Aminah A. Razis ◽  
M. Sukeri M. Yusof ◽  
A. Maisara Kadir ◽  
Bohari M. Yamin
Keyword(s):  
Hydrogen Bonds ◽  
Dihedral Angle ◽  
Title Compound ◽  
Intermolecular Hydrogen Bonds ◽  
Intramolecular Hydrogen Bonds ◽  
Compound C ◽  
Intramolecular Hydrogen

The title compound, C16H16N2OS, adopts a trans–cis configuration of the 4-methylbenzoyl and 4-methylphenyl groups, with respect to the thiono S atom across the thiourea C—N bonds. The dihedral angle between the two groups is 10.36 (8)°. The structure is stabilized by intermolecular hydrogen bonds which form dimers. There are also intramolecular hydrogen bonds.

scholarly journals A novel сalcium trifluoroacetate structure

2021 ◽  
Vol 16 (4) ◽  
pp. 352-362
Author(s):  
A. A. Vasilyeva ◽  
T. Yu. Glazunova ◽  
D. S. Tereshchenko ◽  
E. Kh. Lermontova
Keyword(s):  
Thermal Decomposition ◽  
Hydrogen Bonds ◽  
Trifluoroacetic Acid ◽  
Calcium Fluoride ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
Intramolecular Hydrogen Bonds ◽  
X Ray ◽  
Cell Parameters ◽  
Intramolecular Hydrogen

Objectives. The study was devoted to considering the features of the synthesis and crystal structure of calcium trifluoroacetate Ca2(CF3COO)4·8CF3COOH and investigating the products of its thermal behavior.Methods. The compositions of the proposed structural form were characterized by various physicochemical methods (X-ray diffraction, IR spectroscopy), and the products of thermal decomposition were determined under dynamic vacuum conditions.Results. The reaction between calcium carbonate and 99% trifluoroacetic acid yielded a new structural type of calcium trifluoroacetate Ca2(CF3COO)4·8CF3COOH (I) in the form of colorless prismatic crystals unstable air. X-ray diffraction results confirmed the composition I: space group P21, with unit cell parameters: a = 10.0193(5) Å, b = 15.2612(7) Å, c = 16.3342(8) Å, β = 106.106(2)°, V = 2399.6(2) Å3, Z = 2. The structure is molecular, constructed from Ca2(CF3COO)4·8CF3COOH dimers. The end molecules of the trifluoroacetic acid were involved in the formation of intramolecular hydrogen bonds with oxygen atoms of the bidentate bridging anions CF3COO−. There were strongly pronouncedsymmetric and asymmetric absorption bands of COO and CF3-groups in the IR spectrum of the resulting compound in the range of 1200–1800 cm−1. The definite peak of the oscillation of the OH-group at 3683 cm−1 corresponds to the trifluoroacetic acid molecules present in the structure. The broadpeak of the valence oscillations in the range of 3300–3500 cm−1 is caused by the presence of intramolecular hydrogen bonds. Decomposition began at 250°C and 10−2 mm Hg with calcium fluoride CaF2 as the final decomposition product.Conclusions. We obtained a previously undescribed calcium–trifluoroacetic acid complex whose composition can be represented by Ca2(CF3COO)4·8CF3COOH. The crystal island structure is a dimeric molecule where the calcium atoms are bound into dimers by four trifluoroacetate groups. The complex was deposited in the Cambridge Structural Data Bank with a deposit number CCDC 2081186. Although the compound has a molecular structure, thermal decomposition leads to the formation of calcium fluoride characterized by a small particle size, which may further determine its applications.

scholarly journals Unusual Effects of Intramolecular Hydrogen Bonds and Dipole Interaction on FTIR and NMR of Some Imines

2019 ◽  
pp. 1-6 ◽  
Author(s):  
Elham Abdalrahem Bin Selim ◽  
Mohammed Hadi Al–Douh
Keyword(s):  
Hydrogen Bonds ◽  
Chemical Shifts ◽  
Dipole Interaction ◽  
Intramolecular Hydrogen Bonds ◽  
X Ray ◽  
X Ray Crystallography ◽  
Dipole Interactions ◽  
Intramolecular Hydrogen

Unusual effects of intramolecular hydrogen bonds and dipole interactions are investigated using FTIR, NMR and X-Ray crystallography analyses of some imines. These phenomena affect both FTIR absorptions and chemical shifts.

Unusual crystal structure ofN-substituted maleamic acid – very strong effect of intramolecular hydrogen bonds

2014 ◽  
Vol 70 (6) ◽  
pp. 942-947 ◽  
Author(s):  
Raju Francis ◽  
Pallepogu Raghavaiah ◽  
Kuruvilla Pius
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Single Crystal ◽  
Amide Group ◽  
Intramolecular Hydrogen Bonds ◽  
X Ray ◽  
Planar Molecule ◽  
C And N ◽  
Maleamic Acid ◽  
Intramolecular Hydrogen

N-Carbamylmaleamic acid (malur) undergoes cyclodehydration under favourable conditions, as expected, to giveN-carbamyl maleimide.N-(Carboxymethyl) maleamic acid (malgly), however, does not undergo a similar cyclization reaction. Strong π bonding between the C and N of the amide group as well as two intramolecular hydrogen bonds makesmalglya planar molecule, as revealed by single-crystal X-ray studies.

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