Experimental and Computational Studies on Aminoguanidine Free Base, Monocation and Dication, Part I: The Crystal and Molecular Structure of Aminoguanidine Monohydrochloride and the ab Initio Structure of the Endiamine Tautomer of Aminoguanidine Free Base

1996 ◽  
Vol 51 (12) ◽  
pp. 1771-1778 ◽  
Author(s):  
Jere T. Koskinen ◽  
Mikko Koskinen ◽  
Ilpo Mutikainen ◽  
Berit Mannfors ◽  
Hannu Elo
Keyword(s):  
Molecular Structure ◽  
Ab Initio ◽  
Density Functional ◽  
Crystal And Molecular Structure ◽  
Free Base ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Ab Initio Structure ◽  
Divalent Salts

The crystal and molecular structure of aminoguanidine monohydrochloride, CN4H7+.CL- in which aminonoguanidine exists in the monocation form, was determined by single-crystal X-ray diffraction. The structure of the monocation is largely similar to that of aminoguanidine dication as present in previously studied divalent salts. The monocation was found to exist in the form of the tautom er that allows strong resonance in the guanyl group. As compared to the dication, the terminal hydrazine nitrogen atom bears one hydrogen atom less. The monocation is planar, the only atoms deviating from the plane being the hydrogens attached to the terminal hydrazine nitrogen. Quantum chemical calculations on the endiamine tautomer of aminoguanidine free base as well as on aminoguanidine monocation and dication were also perform ed by using the HF and MP2 ab initio methods and also the B3- LYP and B-LYP methods based on density functional theory. On the basis of the calculations, a predicted structure of the endiamine tautom er of aminoguanidine free base is presented

scholarly journals Molecular structure investigation by ab initio, DFT and X-ray diffraction of thiazole-derived compound

2014 ◽  
Vol 70 (a1) ◽  
pp. C1234-C1234
Author(s):  
Manel Boulakoud ◽  
Abdelkader Chouaih ◽  
Fodil Hamzaoui
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Intermolecular Hydrogen Bond ◽  
Basis Set ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Cell Parameters

We report here the synthesis of Z-3-(2-Ethoxyphenyl)-2-(2-Ethoxyphenyl)-1,3-Thiazolidin-4-one compound. The crystal structure has been determined by X-ray diffraction. The compound crystallizes in the monoclinic system with space group P21/n and cell parameters: a = 9.4094(10), b = 9.3066(10), c = 20.960(2) Å, β=99.0375(10)0, V = 1812.7(3)Å3 and Z = 4. The structure has been refined to a final R = 0.05 for 2083 observed reflections. The refined structure was found to be significantly non planar. The molecule exhibits intermolecular hydrogen bond of type C–H...O, C–H...N and C–H...S. Ab initio calculations were also performed at Hartree–Fock and density functional theory levels. The full HF and DFT geometry optimization was carried out using 6-31G(d,p) basis set. The observed molecular structure is compared with that calculated by both HF and density functional theory methods. The optimized geometry of the title compound was found to be consistent structure determined by X-ray diffraction.

scholarly journals Hydrosilyation of CO2 using a silatrane hydride: structural characterization of a silyl formate compound

2021 ◽  
Vol 99 (2) ◽  
pp. 259-267
Author(s):  
Serge Ruccolo ◽  
Erika Amemiya ◽  
Daniel G. Shlian ◽  
Gerard Parkin
Keyword(s):  
Molecular Structure ◽  
Density Functional Theory ◽  
Oxygen Atom ◽  
Structural Characterization ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray

The silatrane hydride compound, [N(CH2CH2O)3]SiH, reacts with CO2 in the presence of the [tris(2-pyridylthio)methyl]zinc hydride complex, [Tptm]ZnH, to afford the silyl formate and methoxide derivatives, [N(CH2CH2O)3]SiO2CH and [N(CH2CH2O)3]SiOCH3. The molecular structure of [N(CH2CH2O)3]SiO2CH has been determined by X-ray diffraction, thereby demonstrating that the formate ligand adopts a distal conformation in which the uncoordinated oxygen atom resides with a trans-like disposition relative to silicon. Density functional theory calculations indicate that the atrane motif of [N(CH2CH2O)3]SiO2CH is flexible, such that the energy of the molecule changes relatively little as the Si···N distance varies over the range 2.0–3.0 Å.

scholarly journals Experimental and theoretical studies of 4-[(4-methyl-5-phenyl- 4H1,2,4-triazol-3-yl)sulfanyl]benzene-1,2-dicarbonitrile

2016 ◽  
Vol 35 (2) ◽  
pp. 169
Author(s):  
Ufuk Çoruh ◽  
Reşat Ustabaş ◽  
Hakkı Türker Akçay ◽  
Emra Menteşe ◽  
Ezequiel M. Vazquez Lopez
Keyword(s):  
Molecular Structure ◽  
Density Functional ◽  
Basis Set ◽  
Geometrical Parameters ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Ft Ir ◽  
Experimental And Theoretical Studies ◽  
Homo Lumo

In this study, 4-[(4-methyl-5-phenyl-4<em>H</em>-1,2,4-triazol-3-yl)sulfanyl]benzene-1,2-dicarbonitrile was synthesized and its molecular structure was characterized by means of FT-IR and X-ray diffraction methods. The crystal is monoclinic and belongs to the P21/n space group. There are three weak intermolecular C-H…N type hydrogen bonds in the molecular structure. The geometrical parameters, vibration frequencies, HOMO–LUMO energies, and molecular electrostatic potential (MEP) map of the compound (3) in ground state were calculated by using density functional theory (DFT/B3LYP) with the 6-311G(d) basis set. Calculated geometrical parameters were compared with X-ray diffraction geometric parameters. On the other hand, theoretical and experimental FT-IR results were also compared.

Low barrier hydrogen bond in protonated proton sponge. X-ray diffraction, infrared, and theoretical ab initio and density functional theory studies

2003 ◽  
Vol 119 (8) ◽  
pp. 4313-4319 ◽  
Author(s):  
Agnieszka J. Bieńko ◽  
Zdzisław Latajka ◽  
Wanda Sawka-Dobrowolska ◽  
Lucjan Sobczyk ◽  
Valery A. Ozeryanskii ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Hydrogen Bond ◽  
Ab Initio ◽  
Density Functional ◽  
Proton Sponge ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray

A DFT study of spherands containing five anisyl groups — Highly preorganized to bind the alkali metal

2006 ◽  
Vol 84 (8) ◽  
pp. 1045-1049 ◽  
Author(s):  
Shabaan AK Elroby ◽  
Kyu Hwan Lee ◽  
Seung Joo Cho ◽  
Alan Hinchliffe
Keyword(s):  
Density Functional Theory ◽  
Binding Energy ◽  
Density Functional ◽  
Ionic Radius ◽  
Binding Energies ◽  
Cavity Size ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Good Agreement

Although anisyl units are basically poor ligands for metal ions, the rigid placements of their oxygens during synthesis rather than during complexation are undoubtedly responsible for the enhanced binding and selectivity of the spherand. We used standard B3LYP/6-31G** (5d) density functional theory (DFT) to investigate the complexation between spherands containing five anisyl groups, with CH2–O–CH2 (2) and CH2–S–CH2 (3) units in an 18-membered macrocyclic ring, and the cationic guests (Li+, Na+, and K+). Our geometric structure results for spherands 1, 2, and 3 are in good agreement with the previously reported X-ray diffraction data. The absolute values of the binding energy of all the spherands are inversely proportional to the ionic radius of the guests. The results, taken as a whole, show that replacement of one anisyl group by CH2–O–CH2 (2) and CH2–S–CH2 (3) makes the cavity bigger and less preorganized. In addition, both the binding and specificity decrease for small ions. The spherands 2 and 3 appear beautifully preorganized to bind all guests, so it is not surprising that their binding energies are close to the parent spherand 1. Interestingly, there is a clear linear relation between the radius of the cavity and the binding energy (R2 = 0.999).Key words: spherands, preorganization, density functional theory, binding energy, cavity size.

On tungstates of divalent cations (III) – Pb5O2[WO6]

2020 ◽  
Vol 235 (8-9) ◽  
pp. 311-317
Author(s):  
Stephan G. Jantz ◽  
Florian Pielnhofer ◽  
Henning A. Höppe
Keyword(s):  
Crystal Structure ◽  
Thermal Analysis ◽  
Quantum Chemical ◽  
Density Functional ◽  
Divalent Cations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
First Results ◽  
Electrostatic Calculations

Abstract${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{WO}}_{6}\right]$ was discovered as a frequently observed side phase during our investigation on lead tungstates. Its crystal structure was solved by single-crystal X-ray diffraction ($P{2}_{1}/n$, $a=7.4379\left(2\right)$ Å, $b=12.1115\left(4\right)$ Å, $c=10.6171\left(3\right)$ Å, $\beta =90.6847\left(8\right)$°, $Z=4$, ${R}_{\text{int}}=0.038$, ${R}_{1}=0.020$, $\omega {R}_{2}=0.029$, 4188 data, 128 param.) and is isotypic with ${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{Te}}_{6}\right]$. ${\text{Pb}}_{5}{\text{O}}_{2}\left[{\text{WO}}_{6}\right]$ comprises a layered structure built up by non-condensed [WO6]${}^{6-}$ octahedra and ${\left[{\text{O}}_{4}{\text{Pb}}_{10}\right]}^{12+}$ oligomers. The compound was characterised by spectroscopic measurements (Infrared (IR), Raman and Ultraviolet–visible (UV/Vis) spectra) as well as quantum chemical and electrostatic calculations (density functional theory (DFT), MAPLE) yielding a band gap of 2.9 eV fitting well with the optical one of 2.8 eV. An estimation of the refractive index based on the Gladstone-Dale relationship yielded $n\approx 2.31$. Furthermore first results of the thermal analysis are presented.

Crystal and molecular structure of diorganoammonium oxalatotrimethylstannate, [R2NH2][Me3Sn(C2O4)] (R=i-Bu, cyclohexyl)

2011 ◽  
Vol 34 (5-6) ◽  
pp. 127-130 ◽  
Author(s):  
Yaya Sow ◽  
Libasse Diop ◽  
Kieran C. Molloy ◽  
Gabrielle Kociok-Köhn
Keyword(s):  
Molecular Structure ◽  
Hydrogen Bonds ◽  
Diffraction Study ◽  
Crystal And Molecular Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Trans Complex ◽  
A Chain ◽  
Distorted Trigonal Bipyramidal

Abstract The title compounds [R2NH2][C2O4SnMe3](R=i-Bu, Cy), in which tin atoms adopt a distorted trigonal bipyramidal configuration, have been prepared and submitted to an X-ray diffraction study. These compounds have been obtained from the reaction of (Cy2NH2)2C2O4·H2O or (i-Bu2NH2)2C2O4 with SnMe3Cl. In both [R2NH2][C2O4SnMe3] compounds, the trans complex has an almost regular trigonal bipyramidal geometry around the tin atom. The SnMe3 residues are connected as a chain with bridging oxalate anions in a trans-SnC3O2 framework, the oxygen atoms being in axial positions. The cations connect linear adjacent chains through NH…O hydrogen bonds giving layered structures.

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