A simple and versatile close-packing model for student use and overhead projection

1977 ◽  
Vol 54 (11) ◽  
pp. 685
Author(s):  
D. Robert Lloyd ◽  
Jack Silver
Keyword(s):  
Close Packing ◽  
Packing Model ◽  
Overhead Projection

Triorganotin Fluoride Structures: A Ligand Close-Packing Model with Predominantly Ionic Sn−F Bonds

2003 ◽  
Vol 2003 (1) ◽  
pp. 164-174 ◽  
Author(s):  
Jens Beckmann ◽  
Dagmar Horn ◽  
Klaus Jurkschat ◽  
Fred Rosche ◽  
Markus Schürmann ◽  
...  
Keyword(s):  
Close Packing ◽  
Packing Model

Molecular coordination numbers in crystal structures of organic compounds

2000 ◽  
Vol 56 (3) ◽  
pp. 501-511 ◽  
Author(s):  
E. V. Peresypkina ◽  
V. A. Blatov
Keyword(s):  
Crystal Structures ◽  
Organic Compounds ◽  
Arbitrary Shape ◽  
Short Range ◽  
Close Packing ◽  
Geometrical Analysis ◽  
Coordination Numbers ◽  
Topological Parameters ◽  
Packing Model

The calculation of molecular coordination numbers (MCNs), and topological and geometrical analysis of the environment of molecules in the crystal structures of 23 067 organic compounds, shows that Kitaigorodskii's close-packing model, assuming the predominance of MCN = 12, works correctly in only a few cases, whereas MCN = 14 is the most frequent. To explain this fact the close-packing model is extended with the model of the thinnest covering of space by deformable molecules. It is shown that the packing of molecules of arbitrary shape and composition can be better described with geometrical, but not topological, parameters of their short-range environment, which is conveniently characterized by molecular Voronoi–Dirichlet polyhedra.

Bonding and Geometry of OCF3-, ONF3, and Related Molecules in Terms of the Ligand Close Packing Model

1998 ◽  
Vol 37 (26) ◽  
pp. 6884-6889 ◽  
Author(s):  
Ronald J. Gillespie ◽  
Edward A. Robinson ◽  
George L. Heard
Keyword(s):  
Close Packing ◽  
Packing Model

Crystal structure images of large gold clusters and growing crystals by HRTEM

1984 ◽  
Vol 42 ◽  
pp. 428-429
Author(s):  
L.R. Wallenberg ◽  
J.-O. Bovin ◽  
G. Schmid
Keyword(s):  
Crystal Structure ◽  
Nucleation And Growth ◽  
Close Packing ◽  
Gold Clusters ◽  
Molecular Weight Determination ◽  
Growth Mechanisms ◽  
Starting Point ◽  
Different Types ◽  
Nucleation And Growth Mechanisms ◽  
Points Of View

Metallic clusters are interesting from various points of view, e.g. as a mean of spreading expensive catalysts on a support, or following heterogeneous and homogeneous catalytic events. It is also possible to study nucleation and growth mechanisms for crystals with the cluster as known starting point.Gold-clusters containing 55 atoms were manufactured by reducing (C6H5)3PAuCl with B2H6 in benzene. The chemical composition was found to be Au9.2[P(C6H5)3]2Cl. Molecular-weight determination by means of an ultracentrifuge gave the formula Au55[P(C6H5)3]Cl6 A model was proposed from Mössbauer spectra by Schmid et al. with cubic close-packing of the 55 gold atoms in a cubeoctahedron as shown in Fig 1. The cluster is almost completely isolated from the surroundings by the twelve triphenylphosphane groups situated in each corner, and the chlorine atoms on the centre of the 3x3 square surfaces. This gives four groups of gold atoms, depending on the different types of surrounding.

A Robust, Porous and Solution-Processable Molecular Crystal Containing Multiple Donor-Acceptor Units

2019 ◽  
Author(s):  
Shengxian Cheng ◽  
Xiaoxia Ma, ◽  
Yonghe He ◽  
Jun He ◽  
Matthias Zeller ◽  
...  
Keyword(s):  
Molecular Crystal ◽  
Bulk Sample ◽  
Intermolecular Forces ◽  
Close Packing ◽  
Molecular Solids ◽  
Molecular Scaffold ◽  
Excellent Thermal Stability ◽  
Crystalline Order ◽  
Donor Acceptor ◽  
Open Packing

We report a curious porous molecular crystal that is devoid of the common traits of related systems. Namely, the molecule does not rely on directional hydrogen bonds to enforce open packing; and it offers neither large concave faces (i.e., high internal free volume) to frustrate close packing, nor any inherently built-in cavity like in the class of organic cages. Instead, the permanent porosity (as unveiled by the X-ray crystal structure and CO<sub>2</sub> sorption studies) arises from the strong push-pull units built into a Sierpinski-like molecule that features four symmetrically backfolded (<b>SBF</b>) side arms. Each side arm consists of the 1,1,4,4-tetracyanobuta-1,3-diene acceptor (TCBD) coupled with the dimethylaminophenyl donor, which is conveniently installed by a cycloaddition-retroelectrocyclization (CA-RE) reaction. Unlike the poor/fragile crystalline order of many porous molecular solids, the molecule here readily crystallizes and the crystalline phase can be easily deposited into thin films from solutions. Moreover, both the bulk sample and thin film exhibit excellent thermal stability with the porous crystalline order maintained even at 200 °C. The intermolecular forces underlying this robust porous molecular crystal likely include the strong dipole interactions and the multiple C···N and C···O short contacts afforded by the strongly donating and accepting groups integrated within the rigid molecular scaffold.

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