ChemInform Abstract: EFFECT OF 2-TRIPHENYLSILYL SUBSTITUTION ON THE MOLECULAR GEOMETRY OF 1,3-DITHIANES. CRYSTAL STRUCTURES OF 2-METHYL-2-TRIPHENYLSILYL-1,3-DITHIANE AND TRANS-2-TRIPHENYLSILYL-1,3-DITHIANE 1-OXIDE

1978 ◽  
Vol 9 (20) ◽  
Author(s):  
R. F. BRYAN ◽  
F. A. CAREY ◽  
O. HERNANDEZ ◽  
I. F. JUN. TAYLOR
2007 ◽  
Vol 62 (7-8) ◽  
pp. 417-424
Author(s):  
Basavalinganadoddy Thimme Gowda ◽  
Sabine Foro ◽  
Jozef Kožíšek ◽  
Hartmut Fuess ◽  

The effect of ring substitution and N-chlorination on the molecular geometry of arylsulphonamides and N-chloro-arylsulphonamides have been studied by determining the crystal structures of 2-methyl- 4-chloro-benzenesulphonamide (2M4CBSA) and the sodium salt of N-chloro-2-methyl-4-chlorobenzenesulphonamide (NaNC2M4CBSA). The results are analyzed along with the crystal structures of benzenesulphonamide, 4-methyl-benzenesulphonamide and 4-chloro-benzenesulphonamide. The crystal structure of NaNC2M4CBSA has also been compared and correlated with the crystal structures of the above compounds and those of the sodium salts of N-chloro-benzenesulphonamide, Nchloro- 4-methyl-benzenesulphonamide, N-chloro-4-chloro-benzenesulphonamide and N-chloro-2,4- dichloro-benzenesulphonamide. The crystal system, space group, formula units and lattice constants in Å of the new structures are: 2M4CBSA: triclinic, P1, Z = 4, a = 7.9030(10), b = 8.6890(10), c = 13.272(2), α = 100.680(10)°, β = 98.500(10)°, γ = 90.050(10)°; NaNC2M4CBSA: monoclinic, C2/c, Z =4, a = 10.9690(10), b = 6.7384(6), c = 30.438(2), β = 98.442(7)°. The structure of 2M4CBSA is quite complex with four molecules in its asymmetric unit. The S-N bond length slightly decreases with substitution of electron-withdrawing groups, while the effect is more pronounced with disubstitution. The structure of NaNC2M4CBSA confirms that there is no interaction between nitrogen and sodium, and Na+ is attached to one of the sulphonyl oxygen atoms. The Na+ coordination sphere involves oxygen atoms from water moleculess of crystallization and neighbouring molecules. The S-N distance of 1.586 Å for the compound is consistent with a S-N double bond. The molecules are held together by hydrogen bonds with distances varying from 2.12 to 2.85 Å.


1980 ◽  
Vol 33 (10) ◽  
pp. 2237 ◽  
Author(s):  
JR Cannon ◽  
CL Raston ◽  
AH White

The crystal structures of the hemi-ethanolate of nitron, C20H16N4(C2H6O)0.5, and of a non-stoichiometric hydrochloride of nitron, C20H16N4(HCl)1.7(H2O)3.3, have been determined by X-ray diffraction from diffractometer data at 295 K and refined by block diagonal least squares to residuals of 0.069 (2049 'observed' reflections) and 0.055 (1915), respectively. Crystals of the hemi-ethanolate of nitron are monoclinic P21/n, a 12.697(6), b 15.821(5), c 19.064(6) Ǻ, β 108.79(3)°, Z 8. Crystals of the non-stoichiometric hydrochloride of nitron are also monoclinic C2/c, a 25.41(1), b 5.968(6), c 29.40(2) Ǻ, β 103.53(5)°, Z 8. Despite some unusual features in their molecular geometry, these structures are consistent with the mesoionic character of nitron.


2014 ◽  
Vol 70 (a1) ◽  
pp. C495-C495
Author(s):  
Colin Groom ◽  
Suzanna Ward ◽  
Neil Feeder ◽  
Elna Pidcock ◽  
Peter Wood ◽  
...  

The crystallographic community has done something remarkable and almost unique in science. It has operated in such a way that the data generated in virtually every experiment reported in a publication is available to all. This data, in the form of individual crystal structures, is valuable not just in itself, but as a collection. To fully exploit the results of a new structure determination, we never analyse a single structure, we analyse it in the context of every previous crystal structure. Our knowledge of molecular geometry and molecular interactions derived from these structural databases is put to routine use in almost every field of chemistry. This presentation will specifically highlight what we can learn from the world's database of small molecule crystal structures and demonstrate how we can apply that knowledge not just to increase our understanding in structural chemistry, but in structural biology too.


Author(s):  
Rahul Shukla ◽  
Christian Ruzié ◽  
Guillaume Schweicher ◽  
Alan R. Kennedy ◽  
Yves H. Geerts ◽  
...  

In this study, the nature and characteristics of the intramolecular and intermolecular interactions in crystal structures of the fluoro-substituted 7,7,8,8-tetracyanoquinodimethane (TCNQ) family of molecules, i.e. F x -TCNQ (x = 0, 2, 4), are explored. The molecular geometry of the reported crystal structures is directly dependent on the degree of fluorination in the molecule, which consequently also results in the presence of an intramolecular N[triple-bond]C...F—C π-hole tetrel bond. Apart from this, the energy framework analysis performed along the respective transport planes provides new insights into the energetic distribution in this class of molecules.


2021 ◽  
Vol 68 (1) ◽  
pp. 144-150
Author(s):  
Una Glamočlija ◽  
Selma Špirtović-Halilović ◽  
Mirsada Salihović ◽  
Iztok Turel ◽  
Jakob Kljun ◽  
...  

Using X-ray single crystal diffraction, the crystal structures of biologically active benzoxazole derivatives were determined. DFT calculation was performed with standard 6-31G*(d), 6-31G** and 6-31+G* basis set to analyze the molecular geometry and compare with experimentally obtained X-ray crystal data of compounds. The calculated HOMO-LUMO energy gap in compound 2 (2-(2-hydroxynaphtalen-1-yl)-4-methyl-7-isopropyl-1,3-benzoxazol-5-ol) is 3.80 eV and this small gap value indicates that compound 2 is chemically more reactive compared to compounds 1 (4-methyl-2-phenyl-7-isopropyl-1,3-benzoxazol-5-ol) and 3 (2-(4-chlorophenyl)-4-methyl-7-isopropyl- 1,3-benzoxazol-5-ol). The crystal structures are stabilized by both intra- and intermolecular hydrogen bonds in which an intermolecular O–H⋅⋅⋅N hydrogen bond generates N3 and O7 chain motif in compounds 1, 2, and 3, respectively. The calculated bond lengths and bond angles of all three compounds are remarkably close to the experimental values obtained by X-ray single crystal diffraction.


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