Search results for "Electron delocalization"
showing 7 items of 7 documents
Electron delocalization in mixed-valence Keggin polyoxometalates. Ab initio calculation of the local effective transfer integrals and its consequence…
2002
We present a quantitative evaluation of the influence of the electron transfer on the magnetic properties of mixed-valence polyoxometalates reduced by two electrons. For that purpose, we extract from valence-spectroscopy ab initio calculations on embedded fragments the value of the transfer integrals between W nearest-neighbor atoms in a mixed-valence alphaPW(12)O(40) polyoxowolframate Keggin anion. In contradiction with what is usually assumed, we show that the electron transfer between edge-sharing and corner-sharing WO(6) octahedra have very close values. Considering fragments of various ranges, we analyze the accuracy of calculations on fragments based on only two WO(5) pyramids which s…
Über Phosphor‐haltige Heterocyclen, II: Molekül‐ und Kristallstruktur von 1,2,3,4,5‐Pentaphenyl‐1λ 5 ‐phosphol‐1‐on
1976
Die Struktur der Titelsubstanz wurde rontgenographisch aus Diffraktometer-Einkristalldaten bestimmt und bis zu einem konventionellen R von 0.076 verfeinert. Der 5-ring besitzt „envelope”-Konformation. Fehlende Planaritat und Bindungslangenverteilung schliesen eine Elektronendelokalisation im λ5-Phospholsystem aus. Das Propellersystem der Phenylsubstituenten bildet eine Cs-symmetrische Doppelschneckenschraube. Die Struktur besteht aus 14-fach koordinierten Molekulen. On Heterocyclic Systems Containing Phosphorus, II: Molecular and Crystal Structure of 1,2,3,4,5-Pentaphenyl-1 λ5-phosphol-1-one The crystal structure of the title compound has been determined from single crystal X-ray data and r…
Comparative Structural Studies of 4-Diazopyrazole Derivatives by X-Ray Diffraction and Theoretical Investigation
2005
The X-Ray crystal and molecular structures of the 4-pyrazol derivatives 3-methyl-4-diazo-5-benzamido-1H-pyrazole (4) and 3-benzamido-5-methyl-1H-pyrazole (3) have been determined. A dimeric structure has been found for the first and polymeric for the second. A comparison of 4 with 1,3-dimethyl-4-diazo-5-benzamido-lH-pyrazole (2) shows differences in the geometrical parameters of the pyrazole ring due to electron delocalization in 2 consequent to the nitrogen negative charge in the latter. Theoretical investigation at the density functional theory (DFT) level shows difference in the molecular electronic distribution of 2 and 4, in agreement with the structural parameters and the IR stretchin…
Synthesis and structure of charge transfer salts of tetrathiafulvalene (TTF) and tetramethyl-TTF with 2,4,7-trinitro and 2,4,5,7-tetranitro-9-fluoren…
2009
Charge transfer salts of tetrathiafulvalene (TTF) and tetramethyltetrathiafulvalene (TMTTF) with the organic acceptors 2,4,7-trinitro-9-fluorenone and 2,4,5,7-tetranitro-9-fluorenone have been prepared and characterized. The compounds (TTF)(TENF) (1), (TTF)3(TRNF)2 (2) and (TMTTF)(TRNF) (3) contain mixed stacks of alternating TTF and nitrofluorenone units. Surprisingly, the degree of charge transfer that occurs in these salts is not controlled solely by the redox potentials of the building blocks, but apparently also by the most effective intermolecular interactions in the solid, as determined from the crystal struc- tures obtained. These three compounds exhibit poor electron delocalization…
Molecular Materials from Polyoxometalates
2006
The present article highlights recent results and provide a perspective of the interest of polyoxometalates as inorganic component of molecular materials with active physical properties. Three different aspects will be presented: i) The interest of the magnetic and mixed valence clusters provided by polyoxometalate chemistry in molecular magnetism; ii) The use of these inorganic anions as magnetic component of crystalline conducting materials based on organic donor molecules; iii) The construction of well-organized films of polyoxometalate monolayers by using the Langmuir-Blodgett technique.
MVPACK: a package to calculate energy levels and magnetic properties of high nuclearity mixed valence clusters.
2010
We present a FORTRAN code based on a new powerful and efficient computational approach to solve the double exchange problem for high-nuclearity MV clusters containing arbitrary number of localized spins and itinerant electrons. We also report some examples in order to show the possibilities of the program.
π-Electron delocalization in 2-benzoyl-5-phenylpyrazolidin-3-one
2018
Abstract The crystal and molecular structures of 2-benzoyl-5-phenylpyrazolidin-3-one have been characterized by X-ray diffraction along with density functional theory studies. Cinnamic acid chloride was reacted with benzhydrazide, yielding 2-benzoyl-5-phenylpyrazolidin-3-one. This product was formed in the transformation comprising the nucleophilic addition of benzhydrazide to the styryl fragment of the α,β-unsaturated arrangement and subsequent cyclization. The molecule contains two benzene rings and one five-membered heterocyclic ring with an N–N single bond. The five-membered ring is composed of three atoms of sp 3 hybridization and two atoms of sp 2 hybridization, which cause the flatte…