Coherent X‐Ray Scattering for the Hydrogen Atom in the Hydrogen Molecule
01 May 1965-Journal of Chemical Physics (American Institute of PhysicsAIP)-Vol. 42, Iss: 9, pp 3175-3187
TL;DR: In this paper, the x-ray form factors for a bonded hydrogen in the hydrogen molecule have been calculated for a spherical approximation to the bonded atom, and the corresponding complex scattering factors have also been calculated.
Abstract: The x‐ray form factors for a bonded hydrogen in the hydrogen molecule have been calculated for a spherical approximation to the bonded atom. These factors may be better suited for the least‐squares refinement of x‐ray diffraction data from organic molecular crystals than those for the isolated hydrogen atom. It has been shown that within the spherical approximation for the bonded hydrogens in H2, a least‐squares refinement of the atomic positions will result in a bond length (Re value) short of neutron diffraction or spectroscopic values. The spherical atoms are optimally positioned 0.07 A off each proton into the bond. A nonspherical density for the bonded hydrogen atom in the hydrogen molecule has also been defined and the corresponding complex scattering factors have been calculated. The electronic density for the hydrogen molecule in these calculations was based on a modified form of the Kolos—Roothaan wavefunction for H2. Scattering calculations were made tractable by expansion of a plane wave in spheroidal wavefunctions.
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TL;DR: In this paper, the reaction of zirconocene dichloride with 2 equiv of butyllithium and 1-trimethylsilylpropyne yields yellow 1,1-bis(cyclopentadienyl)-3,4-dimethyl-2,5-biszirconacyclopenta-2.4-diene, 1.
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TL;DR: In this paper, Batiment sci phys,inst cristallog,ch-1015 lausanne dorigny,switzerland. Reference LGSA-ARTICLE-1981-007
Abstract: Note: Batiment sci phys,inst cristallog,ch-1015 lausanne dorigny,switzerland. Reference LGSA-ARTICLE-1981-007doi:10.1002/hlca.19810640613 Record created on 2005-11-09, modified on 2017-05-12
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TL;DR: In this article, a transition metal-stabilized methylene ligand was shown to be the alkyl group of the organic precursor, and the molecular geometry of the bridging ligands CH2 and CO were established from 2718 unique reflections collected with a computer-controlled diffractometer.
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TL;DR: In this paper, the synthesis and properties of the methyllithium complexes of nickel (0) of the type (n-donor)m-(LiCH3)Ni0(π-Ligand)n1 (1a-c, 16a−c, 20a−C) with Chelataminen oder THF als n-donors and CDT2, Ethen oder CO als π-liganden berichtet.
Abstract: Es wird uber die Synthese und Eigenschaften der Methyllithium-Komplexe von Nickel(0) (n-Donor)m(LiCH3)Ni0(π-Ligand)n1 (1a–c, 16a–c, 20a–c) mit Chelataminen oder THF als n-Donoren und CDT2 , Ethen oder CO als π-Liganden berichtet. Die Struktur von (PMDTA)(LiCH3)Ni(C2H4)2 (1b) wurde rontgenographisch bestimmt. — In diesen at-Komplexen ist eine carbanionische Methylgruppe uber eine σ-Bindung an ein Nickelatom gebunden, dessen Akzeptorstarke von den π-Liganden abhangt. Chemische und spektroskopische Eigenschaften der Komplexe lassen fur CDT oder Ethen als π-Liganden auf vergleichsweise polare, fur den CDT-Komplex in Losung dazu thermolabile NiCH3-Bindungen schliesen, wahrend fur den Carbonyl-Komplex aufgrund von 13C-NMR-Daten eine uberwiegend kovalente NiCH3-Bindung anzunehmen ist. Die Befunde stehen mit folgender Reihe zunehmender Akzeptorstarke im Einklang: Ni(CDT) < Ni(C2H4)2 < Ni(CO)3.
On the Lewis Acidity of Nickel(0), I. Methyllithium Complexes of Nickel(0)
The synthesis and properties of the methyllithium complexes of nickel(0) of the type (n-Donor)m-(LiCH3)Ni0(π-Ligand)n1 (1a–c, 16a–c, 20a–c) [n-Donor = chelating amine or THF; π-Ligand = CDT2, ethene, or CO] are described. The structure of (PMDTA)(LiCH3)Ni(C2H4)2 (1b) has been determined by X-ray crystallography. — In these ate complexes, a carbanionic methyl group is σ-bonded to a nickel atom, the acceptor strength of which depend on the π-ligands. The chemical and spectroscopic properties indicate that the NiCH3 bond in the carbonyl complex is largely covalent whereas in the CDT and ethene compounds it is more polar. The CDT complex is thermolabile in solution. The findings are in agreement with the following series of increasing acceptor strength: Ni(CDT) < Ni(C2H4)2 < Ni(CO)3.
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TL;DR: The crystal structures of diquabis(p-chlorophenoxyacetato)copper(II) (1) and diaquabis(phenoxyacetatos)zinc(II, II) (2) have been determined by X-ray methods from diffractometer data and refined by least squares to R 03059 (1), and 03032 (2), for 999 and 1472 'observed' reflections respectively.
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TL;DR: In this article, the quantum mechanical wave functions of molecules are discussed and an attempt is made to effect a simultaneous regional and physical partitioning of the molecular density, the molecular pair density, and the molecular energy, in such a way that meaningful concepts can be associated with the density and energy fragments thus formed.
Abstract: The quantum mechanical wave functions of molecules are discussed. An attempt is made to effect a simultaneous regional and physical partitioning of the molecular density, the molecular pair density, and the molecular energy, in such a way that meaningful concepts can be associated with the density and energy fragments thus formed. The origin of chemical binding is interpreted in terms of the concepts formulated in the partitioning process. (T.F.H.)
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TL;DR: The solution of Schroedinger's equation for the normal hydrogen molecule is approximated by the function $C[{e}^{\ensuremath{-}\frac{z({r}_{1}+{p}_{2})}{a}}+{e^{\ensem{-]-{m{e})+{m}−m{n}−n}]$ where m is the distance of one of the electrons to the two nuclei, and r is the distances of one electron to the other electron.
Abstract: The solution of Schroedinger's equation for the normal hydrogen molecule is approximated by the function $C[{e}^{\ensuremath{-}\frac{z({r}_{1}+{p}_{2})}{a}}+{e}^{\ensuremath{-}\frac{z({r}_{2}+{p}_{1})}{a}}]$ where $a=\frac{{h}^{2}}{4{\ensuremath{\pi}}^{2}m{e}^{2}}$, ${r}_{1}$ and ${p}_{1}$ are the distances of one of the electrons to the two nuclei, and ${r}_{2}$ and ${p}_{2}$ those for the other electron. The value of $Z$ is so determined as to give a minimum value to the variational integral which generates Schroedinger's wave equation. This minimum value of the integral gives the approximate energy $E$. For every nuclear separation $D$, there is a $Z$ which gives the best approximation and a corresponding $E$. We thus obtain an approximate energy curve as a function of the separation. The minimum of this curve gives the following data for the configuration corresponding to the normal hydrogen molecule: the heat of dissociation = 3.76 volts, the moment of inertia ${J}_{0}=4.59\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}41}$ gr. ${\mathrm{cm}}^{2}$, the nuclear vibrational frequency ${\ensuremath{
u}}_{0}=4900$ ${\mathrm{cm}}^{\ensuremath{-}1}$.
292 citations
TL;DR: In this paper, a simple wave function for the normal state of the hydrogen molecule, in which both the atomic and ionic configurations are taken into account, was set up and treated by a variational method.
Abstract: A simple wave function for the normal state of the hydrogen molecule, in which both the atomic and ionic configurations are taken into account, was set up and treated by a variational method. The dissociation energy was found to be 4.00 v.e. as compared to the experimental value of 4.68 v.e. and Rosen's value of 4.02 v.e. obtained by use of a function involving complicated integrals. It was found that the atomic function occurs with a coefficient 3.9 times that of the ionic function. A similar function with different screening constants for the atomic and ionic parts was also tried. It was found that the best results are obtained when these screening constants are equal. The addition of Rosen's term to the atomic‐ionic function resulted in a value of 4.10 v.e. for the dissociation energy.
253 citations
133 citations