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91.
Using normal coordinate analysis, the infrared spectrum of cyclopentanone has been computed as the geometry is modified from the planar form to those in which the geometry about the 5-membered ring looks like 2-norbornanone and also like 7-norbornanone. The computed v
co of cyclopentanone is 1739.9 cm–1 compared to the experimental value of 1740 cm–1.As the cyclopentanone ring is deformed to resemble either the 2-norbornanone or the 7-norbornanone ring system, the computed v
co is too low using the force fields that give good agreement with experimental value for cyclopentanone. The carbonyl force constant had to be increased from 9.7 to 10.0 mdynes/Å for the 2-norbornanone-like model and to 10.4 mdynes/Å for the 7-model system to give v
co values in agreement with the experimental values.
Zusammenfassung Mit Hilfe der Normalkoordinaten-Analyse wird das Infrarotspektrum des Zyklopentanons berechnet, wobei die Geometrie von der planaren Form bis zu der Form, bei der die Geometrie am Fünfring derjenigen des 2-Norbornanons oder auch des 7-Norbornanons ähnlich wird, variiert wird. Der berechnete Wert von v co des Zyklopentanons ist 1739,9 cm–1, während der experimentelle Wert 1740 cm–1 beträgt. Bei den angegebenen Deformationen des Zyklopentanonrings wird der berechnete Wert von v co zu niedrig, wenn man die Kraftfelder zugrunde legt, die für das Zyklopentanon gute Übereinstimmung mit dem Experiment liefern. Die Carbonylkraftkonstanten mußten von 9,7 auf 10,0 m dyn/Å für das 2-Norbornanon-Modell sowie auf 10,4 m dyn/Å für das 7-Norbornanon erhöht werden, um den Wert von v co in Übereinstimmung mit dem Experiment zu bringen.
Résumé Le spectre infra-rouge de la cyclopentanone a été calculé en employant l'analyse en coordonnées normales lorsque l'on modifie la géométrie depuis la forme plane jusqu'aux formes o u les configurations sur le noyau pentagonal ressemblent à celles de la 2-norbornanone et de la 7-norbornanone. La fréquence co calculée pour la cyclopentanone est 1739.8 cm–1 comparée à la valeur expérimentale de 1740 cm–1. Lorsque l'on déforme le cycle de la cyclopentanone comme indiqué ci-dessus, la valeur calculée de co est trop faible si l'on emploie les champs de force qui donnent un bon accord avec la valeur expérimentale pour la cyclopentanone. La constante de force du carbonyle doit etre augmentée de 9,7 à 10,0 mdynes/Å pour le modèle analogue à la 2-norbornanone et de 9,7 à 10,4 mdynes/Å pour le modèle analogue à la 7-norbornanone.相似文献
92.
Calaminici P Jug K Köster AM Arbez-Gindre C Screttas CG 《Journal of computational chemistry》2002,23(2):291-297
This paper presents calculations of dipole moments (mu), static polarizabilities (alpha), and first hyperpolarizabilities (beta) of phosphonic acid stilbene derivatives calculated in the framework of density functional theory. These calculations were performed using a finite field approach implemented in the density functional program ALLCHEM and were of an all-electron type using local exchange-correlation functional and specially designed basis sets. The molecular structures have been fully optimized using the semiempirical program MSINDO. Some of the investigated stilbenes have been synthesized very recently while others are described for the first time. Donor and acceptor groups of these analogues have been modified and the influence of these changes on the first hyperpolarizabilities has been investigated. This work demonstrates that the nonlinear optical response beta of these compounds increases dramatically when the acceptor moiety is displaced by analogues containing alkali metal groups. A general mechanism for the design of novel nonlinear optical materials with large first hyperpolarizabilities is described. 相似文献
93.
Oliver Moers Violeta Latorre Karl‐Heinz Nagel Armand Blaschette Peter G. Jones 《无机化学与普通化学杂志》2003,629(1):83-90
Polysulfonylamines. CLX. Crystal Structures of Metal Di(methanesulfonyl)amides. 10. The Three‐Dimensional Coordination Polymers M[(CH3SO2)2N], where M is Potassium, Rubidium, Cesium (Isotypic Structures for M = K, Rb) Low‐temperature X‐ray crystal structures are reported for KA (monoclinic, space group P21/c, Z′ = 1), RbA (isotypic and isostructural with KA), and CsA (monoclinic, P21/n, Z′ = 1), where A— denotes the anion obtained by deprotonation of the strong nitrogen acid (MeSO2)2NH. In KA and RbA, the anion is distorted into a rare C1 conformation, whereas the standard C2 conformation is retained in the cesium complex. The structures consist of three‐dimensional coordination networks, in which each cation adopts an irregular (O6N)‐heptacoordination by forming close contacts to one (O, N)‐chelating, one (O, O)‐chelating and three κ1O‐bonding ligands; however, the coordination number for Cs+ is effectively increased to 8 by a very short Cs···Cs contact distance of 422.5 pm. The crystal packings of the isotypic compounds KA and RbA display lamellar layer substructures that involve six independent ligand‐metal bonds and comprise an internal cation lamella and peripheral regions built up from anion monolayers; the 3D framework is completed by one independent M—O bond cross‐linking the layer substructures. In contrast, CsA features anion monolayers that intercalate planar zigzag chains of cations (Cs···Cs alternatingly 422.5 and 487.5 pm, Cs···Cs···Cs 135.7°), whereby each chain is surrounded and coordinated by four anion stacks and each anion stack connects two cation chains. All structures exhibit close C—H···A interanion contacts consistent with weak hydrogen bonding. 相似文献
94.
95.
Karl Hensen Bjrn Spangenberg Michael Bolte 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(2):208-210
The crystal and molecular structures of two phenanthroline hydrochlorides have been determined at 173 K. 1,10‐Phenanthrolin‐1‐ium chloride, C12H9N2+·Cl?, crystallizes in two stacks of exactly planar molecules. Both stacks are approximately parallel to the (02) plane and the planes composing the different stacks enclose an angle of 13.29 (3)°. Tris(1,10‐phenanthrolin‐1‐ium) dichloride (hydrogen chloride) chloride chloroform solvate, 3C12H9N2+·2Cl?·HCl·Cl?·CHCl3, displays an interesting network of Cl? mediated hydrogen bonds between the two different phenanthrolinium moieties and between a phenanthrolinium and the chloroform solvate. In addition, a hydrogen bond between the HCl and the third Cl? ion is formed. The C—N—C angle at the protonated N atoms is, in all phenanthrolinium units of both structures, significantly larger than the C—N—C angle at the non‐protonated N atom. 相似文献
96.
The 13C spectra of 5,6,9,10-tetradehydrocyclodeca[1,2,3,4-def]-benzo [7,8]biphenylene, 1, and 5,6,9,10-tetradehydrocyclodeca [1,2,3,4-def]-naphtho [2,3-7,8]biphenylene, 2, are reported as are those of a number of simpler acetylenic hydrocarbons used as spectral references. Most of the shifts can be assigned unambiguously. The acetylenic shift assignments were verified by ortho-proton, sp-carbon (1H(1)-13Csp(3)) decoupling experiments. A simple additive shift correlation is found for the hydrocarbons containing unstrained acetylenic groups. However, significant discrepencies are found for the 13C shifts for the strained hydrocarbons 1, 2, 1,2-bis(phenylethynyl)-benzene, 12, and 2,3-bis(phenylethynyl)-naphthalene, 13. The discrepencies are particularily large for carbons near the triple bonds and are attributed to a combination of strain, rehybridization, and other proximity effects related to the interaction between the ortho-substituted acetylenic carbons. 相似文献
97.
First-principles molecular dynamics simulations are carried out to study the structures, dynamics, and electronic properties of liquid Al88Si12 in the temperature ranging from 898 to 1298 K. The temperature dependence of static structure factors, pair correlation functions, and electronic density-of-states are investigated. The structural properties obtained from the simulations are in good agreement with the x-ray diffraction experimental results. 相似文献
98.
Zusammenfassung In Vorstehendem wurde zunächst die Ausführung der von einem von uns ausgearbeiteten Schwefelsäuretitration mittelst Benzidinchlorhydrats nochmals genau beschrieben, sodann wurden die Bedingungen festgestellt, unter denen verschiedene Schwefelsäuremengen am genauesten zu bestimmen waren. Es hat sich dabei herausgestellt, dass die Schwefelsäure bis zu 0,01g H2SO4 herunter nach der beshriebenen Methode auf 1–2 genau bestimmt werden kann. Die Anwendung der Methode auf verschiedene Fälle (Ammoniumsulfat, Alaun, Zinksulfat-heptahydrat, Mohr'sches Salz, Mangansulfat-tetrahydrat), wobei die Metalle in einigen Fällen vorher ausgefällt wurden, bestätigten die zuvor festgestellten Regeln; ausserdem wurde gezeigt, dass beim Ausfällen von Zink, Eisen und Mangan nach dem angegebenen Verfahren Schwefelsäure nicht mitgerissen wird. Die Zeit, welche eine derartige Bestimmung, auch wenn die beschriebenen Ausfällungen vorgenommen werden müssen, bei einiger Uebung erfordert, ist sehr kurz, weil alles Auswaschen und so weiter in Fortfall kommt, so dass auch hier ein Vortheil gegenüber dem gewichtsanalytischen Verfahren vorhanden ist. 相似文献
99.
Karl Hassler 《Monatshefte für Chemie / Chemical Monthly》1982,113(4):421-425
A simple preparation of the title compounds is achieved by reacting Na3P/K3P with stoichiometric mixtures of chlorotriphenylsilane and chlorotrimethylsilane.31P- and29Si-NMR-Data as well as Ir and Raman spectra of the compounds are reported. 相似文献
100.
A mixed metal phosphate incorporating isonicotinate ligand, Cu(HINT)(VO2)(PO4), was hydrothermally synthesized and characterized by single-crystal X-ray diffraction and magnetic susceptibility. This compound crystallizes in the monoclinic space group C2/c with cell parameters a=22.033(1) Å, b=6.2986(3) Å, c=16.0202(9) Å, β=121.001(1), and Z=8. The structure consists of two-dimensional neutral sheets of CuVO2(PO4) with the dipolar isonicotinate ligand being coordinated to Cu ions as a pendent group. Adjacent sheets are connected by hydrogen bonding. Each sheet consists of infinite chains of CuO6 octahedra sharing trans edges which are connected by double chains of vanadyl(V) phosphate via corner sharing. Magnetic study results indicate the presence of intrachain ferromagnetic coupling between Cu ions. The magnetic exchange parameter was estimated as 2J/k =51.83 K based on an S=1/2 equally spaced ferromagnetic chain model. 相似文献