Charge Density Study of Naphthalene Based on X-ray Diffraction Data at Four Different Temperatures and Theoretical Calculations

2004 ◽  
Vol 108 (6) ◽  
pp. 1057-1063 ◽  
Author(s):  
Jette Oddershede ◽  
Sine Larsen
Keyword(s):  
Charge Density ◽  
Diffraction Data ◽  
Theoretical Calculations ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Density Study

Experimental charge density study on FLPs and a FLP reaction product

2018 ◽  
Vol 233 (9-10) ◽  
pp. 723-731
Author(s):  
Christian Joseph Schürmann ◽  
Regine Herbst-Irmer ◽  
Thorsten Lennart Teuteberg ◽  
Daniel Kratzert ◽  
Gerhard Erker ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Charge Density ◽  
Theoretical Calculations ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
X Ray ◽  
Charge Densities ◽  
A Charge ◽  
Density Study ◽  
Experimental Charge Density

Abstract The charge density distribution of the intramolecular frustrated Lewis pair (FLP) Mes2PCH2CH2B(C6F5)2 (1), the phosphinimine HNPMes2CH2CH2B(C6F5)2 (2), as well as a FLP homologue with nitrogen NEt2CHPhCH2B(C6F5)2 (3) were investigated with Bader’s quantum theory of atoms in molecules (QTAIM). The charge densities were derived from both experimental high-resolution X-ray diffraction data (2, 3) and theoretical calculations (1, 3). The QTAIM analysis for the FLPs 1 and 3 showed the prominent B-pnictogen interaction to be weak dative bonds without significant charge-transfer. This holds also true for the B–N–bond of 2. The nitrogen atom is negatively charged, due to a charge transfer from phosphorous and shows features of a sp2-hybridization. The bond is therefore best described as a non-hypervalent Pδ+–Nδ− moiety.

Charge density study of the first mixed-valent tetraphosphete

2014 ◽  
Vol 70 (a1) ◽  
pp. C1345-C1345
Author(s):  
Verena Breuers ◽  
Christian Lehmann ◽  
Walter Frank
Keyword(s):  
Charge Density ◽  
Theoretical Calculations ◽  
X Ray Diffraction ◽  
Ring Plane ◽  
X Ray ◽  
Coordination Behavior ◽  
Rhombic Distortion ◽  
Electrostatic Contribution ◽  
Density Study ◽  
Experimental Charge Density

The first λ3,λ5-tetraphosphete contains a 4π-electron four-membered ring as the central structural unit of a dispirocyclic system and can thus be classified as an analogue to diphosphetes and cyclodiphosphazenes. According to its crystal structure the central P4unit exhibits not only P–P bonds which are of equal length (P1–P2 2,139(1) Å, P1–P2A 2,142(1) Å), but also rhombic distortion (P1–P2–P1A 79,4(1)0, P2–P1–P2A 100,6(1)0).[1] Therefore its electronic structure cannot be described as 'Phosphacyclobutadiene' but either as a bis(ylide) or as a system with delocalized double bonds. After various quantum chemical calculations and an extensive examination of its reaction and coordination behavior failed to answer this question, we addressed the problem via a detailed analysis of its charge density distribution. The experimental charge density based on high resolution X-ray diffraction data collected at low temperature is determined by multipole least squares refinement using the program packageXD2006.[2] In a first step, the static deformation density exhibits charge density which is located mainly outside of the P4ring plane at the λ3-phosphorus atoms but simultaneously redistributed into the P–P bond area. In addition to that, a study of its topological properties and an inspection of the Laplacian of the electron density according to Bader's `Quantum Theory of Atoms in Molecules' (QTAIM)[3] further highlight the bonding features. They reveal polar Si–N, Si–C and P–N bonds with a decreasing amount of electrostatic contribution as well as four valence shell charge concentrations (thus sp3hybridization) at each of the phosphorus atoms. Finally supported by theoretical calculations, the results illustrate the unique bonding situation in the P4unit combining a high ylidic character with unusual not exclusively sigma-like P–P bonds.

Structure and conformational analysis of a bidentate pro-ligand, C21H34N2S2, from powder synchrotron diffraction data and solid-state DFTB calculations

2009 ◽  
Vol 65 (5) ◽  
pp. 639-646 ◽  
Author(s):  
Edward E. Ávila ◽  
Asiloé J. Mora ◽  
Gerzon E. Delgado ◽  
Ricardo R. Contreras ◽  
Luis Rincón ◽  
...  
Keyword(s):  
Solid State ◽  
Diffraction Data ◽  
Density Functional ◽  
Simulated Annealing Algorithm ◽  
Theoretical Calculations ◽  
Tight Binding ◽  
Van Der Waals Interactions ◽  
Am1 Calculations ◽  
X Ray Diffraction ◽  
X Ray

The molecular and crystalline structure of ethyl 1′,2′,3′,4′,4a′,5′,6′,7′-octahydrodispiro[cyclohexane-1,2′-quinazoline-4′,1′′-cyclohexane]-8′-carbodithioate (I) was solved and refined from powder synchrotron X-ray diffraction data. The initial model for the structural solution in direct space using the simulated annealing algorithm implemented in DASH [David et al. (2006). J. Appl. Cryst. 39, 910–915] was obtained performing a conformational study on the fused six-membered rings of the octahydroquinazoline system and the two spiran cyclohexane rings of (I). The best model was chosen using experimental evidence from 1H and 13C NMR [Contreras et al. (2001). J. Heterocycl. Chem. 38, 1223–1225] in combination with semi-empirical AM1 calculations. In the refined structure the two spiran rings have the chair conformation, while both of the fused rings in the octahydroquinazoline system have half-chair conformations compared with in-vacuum density-functional theory (DFT) B3LYP/6-311G*, DFTB (density-functional tight-binding) theoretical calculations in the solid state and other related structures from X-ray diffraction data. Compound (I) presents weak intramolecular hydrogen bonds of the type N—H...S and C—H...S, which produce delocalization of the electron density in the generated rings described by graph symbols S(6) and S(5). Packing of the molecules is dominated by van der Waals interactions.

Experimental electron density study of 1,2,4-triazole at 15 K. A comparison with ab initio-calculations

1997 ◽  
Vol 212 (3) ◽  
Author(s):  
P. Fuhrmann ◽  
T. Koritsánszky ◽  
P. Luger
Keyword(s):  
Ab Initio Calculations ◽  
Ab Initio ◽  
Electron Density ◽  
Diffraction Data ◽  
Topological Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Experimental Electron Density ◽  
Density Study

AbstractTopological properties and the Laplacian function of the electron density of 1,2,4-triazole have been determined from X-ray diffraction data collected at 15 K. 1,2,4-Triazole, C

Electrostatic Properties of Ions in Crystals from X-Ray Diffraction Data

1993 ◽  
Vol 48 (1-2) ◽  
pp. 81-84 ◽  
Author(s):  
Niels K. Hansen
Keyword(s):  
Density Distribution ◽  
Charge Density ◽  
Electrostatic Potential ◽  
Diffraction Data ◽  
Reciprocal Space ◽  
Electrostatic Energy ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
X Ray ◽  
Space Approach

Abstract A procedure for calculating the electrostatic potential and the electrostatic energy of an ion in a crystal is presented. It is based on a mixed direct and reciprocal space approach, and it takes into account the detailed charge density distribution in the crystal which can be obtained from accurate X-ray diffraction measurements.

Charge-Density Distribution and Electrostatic Flexibility of ZIF-8 Based on High-Resolution X-ray Diffraction Data and Periodic Calculations

2015 ◽  
Vol 54 (6) ◽  
pp. 2660-2670 ◽  
Author(s):  
Sladjana B. Novaković ◽  
Goran A. Bogdanović ◽  
Christian Heering ◽  
Gamall Makhloufi ◽  
Djordje Francuski ◽  
...  
Keyword(s):  
High Resolution ◽  
Density Distribution ◽  
Charge Density ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
Charge Density Distribution ◽  
X Ray ◽  
Periodic Calculations
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