Comment on the paper “crystal structure and bond character study of 2,4dichloroacetanilide by NQR”

1976 ◽  
Vol 21 (2) ◽  
pp. 377-381
Author(s):  
Wolfgang Pies ◽  
Alarich Weiss
Keyword(s):  
Crystal Structure ◽  
Character Study ◽  
Bond Character

The search for formal electrostatic effects on molecular conformation and crystal packing: crystal structure of 2,2′′-disubstituted (HversusPPh2) 1,1′-(1,2-phenylene)bis(3-methyl-1H-imidazol-3-ium) bis(trifluoromethanesulfonate)

2016 ◽  
Vol 72 (3) ◽  
pp. 198-202
Author(s):  
Carine Duhayon ◽  
Yves Canac ◽  
Laurent Dubrulle ◽  
Carine Maaliki ◽  
Remi Chauvin
Keyword(s):  
Crystal Structure ◽  
Electrostatic Interactions ◽  
Molecular Conformation ◽  
Crystal Packing ◽  
Relative Orientation ◽  
Electron Delocalization ◽  
Electrostatic Effects ◽  
Conformational Freedom ◽  
The Stability ◽  
Bond Character

Electrostatic interactions between localized integral charges make the stability and structure of highly charged small and rigid organics intriguing. Can σ/π-electron delocalization compensate reduced conformational freedom by lowering the repulsion between identical charges? The crystal structure of the title salt, C14H16N42+·2CF3SO3−, (2), is described and compared with that of the 2,2′′-bis(diphenylphosphanyl) derivative, (4). The conformations of the dications and their interactions with neighbouring trifluoromethanesulfonate anions are first analyzed from the standpoint of formal electrostatic effects. Neither cation exhibits any geometrical strain induced by the intrinsic repulsion between the positive charges. In contrast, the relative orientation of the imidazolium rings [i.e. antifor (2) andsynfor (4)] is controlled by different configurations of the interactions with the closest trifluoromethanesulfonate anions. The long-range arrangement is also found to be specific: beyond the formal electrostatic packing, C—H...O and C—H...F contacts have no definite `hydrogen-bond' character but allow the delineation of layers, which are either pleated or flat in the packing of (2) or (4), respectively.

scholarly journals Crystal structure ofN′′-benzyl-N′′-[3-(benzyldimethylazaniumyl)propyl]-N,N,N′,N′-tetramethylguanidinium bis(tetraphenylborate)

2015 ◽  
Vol 71 (12) ◽  
pp. o1086-o1087
Author(s):  
Ioannis Tiritiris ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Positive Charge ◽  
Planar Geometry ◽  
Methyl Groups ◽  
Two Dimensional ◽  
Single Bond ◽  
Double Bond Character ◽  
Bond Lengths ◽  
Bond Character

In the crystal structure of the title salt, C24H38N42+·2C24H20B−, the C—N bond lengths in the central CN3unit of the guanidinium ion are 1.3364 (13), 1.3407 (13) and 1.3539 (13) Å, indicating partial double-bond character. The central C atom is bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charge is delocalized in the CN3plane. The bonds between the N atoms and the terminal methyl groups of the guanidinium moiety and the four C—N bonds to the central N atom of the (benzyldimethylazaniumyl)propyl group have single-bond character. In the crystal, C—H...π interactions between the guanidinium H atoms and the phenyl C atoms of the tetraphenylborate ions are present, leading to the formation of a two-dimensional supramolecular pattern parallel to theacplane.

Structure and Bonding of Bromoantimonate (III) Complexes with Unusual Valency by Means of NQR and Powder X-Ray Diffraction

1994 ◽  
Vol 49 (1-2) ◽  
pp. 185-192 ◽  
Author(s):  
Tsutomu Okuda ◽  
Yoshihiro Kinoshita ◽  
Hiromitsu Terao ◽  
Koji Yamada
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Bond Length ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Bonding ◽  
Bond Character

Abstract NQR and powder X-ray diffraction were observed for several bromoantimonate (III) complexes which contain CnH2n+1NH3 (n = 1 -3) or (CnH2n+1)2NH2(n = 1 -4) as a cation. The bond character, anion structure, crystal structure, and phase transition are discussed on the basis of the three-center-four-electron bond. A good correlation was found between the halogen NQR frequency and the Sb-X bond length.

scholarly journals Morpholine-4-carboxamidinium sulfate

IUCrData ◽  
2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Ioannis Tiritiris ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Planar Geometry ◽  
Asymmetric Unit ◽  
Sulfate Ion ◽  
Double Bond Character ◽  
Dimensional Network ◽  
Bond Character

The asymmetric unit of the title salt, 2C5H12N3O+·SO42−, comprises two cations and one sulfate ion. In both cations, the C, N and O atoms of the morpholine rings are disordered over two sets of sites, with refined occupancies of 0.849 (3):0.151 (3) for cation I and 0.684 (4):0.316 (4) for cation II. The C—N bond lengths in both central C3N units of the carboxamidinium ions range between 1.253 (12) and 1.362 (5) Å, indicating a degree of double-bond character. The central C atoms are bonded to the three N atoms in a nearly ideal trigonal–planar geometry and the positive charges are delocalized in both CN3planes. The crystal structure is stabilized by a three-dimensional network of N—H...O hydrogen bonds between the cations and the sulfate ion. Scheme tiny font, charges and delocalized bonds almost invisible

scholarly journals Crystal structure of (1-ethoxyethylidene)dimethylazanium tetraphenylborate

2015 ◽  
Vol 71 (12) ◽  
pp. o984-o985
Author(s):  
Ioannis Tiritiris ◽  
Stefan Saur ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Bond Length ◽  
Single Bond ◽  
Charge Delocalization ◽  
Double Bond Character ◽  
Iminium Ions ◽  
Iminium Ion ◽  
Phenyl Rings ◽  
Bond Character

In the cation of the title salt, C6H14NO+·C24H20B−, the C—N bond lengths are 1.297 (2), 1.464 (2) and 1.468 (2) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.309 (2) Å shows double-bond character, pointing towards charge delocalization within the NCO plane of the iminium ion. In the crystal, C—H...π interactions between the iminium H atoms and the phenyl C atoms of the anion are present. The phenyl rings form aromatic pockets, in which the iminium ions are embedded.

scholarly journals Crystal structure ofN-[3-(dimethylamino)propyl]-N′,N′,N′′,N′′-tetramethyl-N-(N,N,N′,N′-tetramethylformamidiniumyl)guanidinium bis(tetraphenylborate)

2015 ◽  
Vol 71 (12) ◽  
pp. o1045-o1046 ◽  
Author(s):  
Ioannis Tiritiris ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Dihedral Angle ◽  
Two Dimensional ◽  
Double Bond Character ◽  
Bond Lengths ◽  
Π Interactions ◽  
Benzene Rings ◽  
Bond Character

In the title salt, C15H36N62+·2C24H20B−, the three N—C bond lengths in the central C3N unit of the bisamidinium ion range between 1.388 (3) and 1.506 (3) Å, indicating single- and double-bond character. Furthermore, four C—N bonds have double-bond character. Here, the bond lengths range from 1.319 (3) to 1.333 (3) Å. Delocalization of the positive charges occurs in the N/C/N and C/N/C planes. The dihedral angle between both N/C/N planes is 70.5 (2)°. In the crystal, C—H...π interactions between H atoms of the cation and the benzene rings of both tetraphenylborate ions are present. The benzene rings form aromatic pockets, in which the bisamidinium ion is embedded. This leads to the formation of a two-dimensional supramolecular pattern along theabplane.

Structure of [μ-S2{Ru(PCy3)('S4')}2] · 2.5 THF ·0.5 Et2O Containing Homochiral Metal Complex Fragments ['S4'2- = 1,2-Bis(mercaptophenylthio)-ethane (2-)]

1999 ◽  
Vol 54 (9) ◽  
pp. 1122-1124 ◽  
Author(s):  
Dieter Sellmann ◽  
Frank W. Heinemann ◽  
Torsten Gottschalk-Gaudig
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Double Bond ◽  
Metal Complex ◽  
Title Compound ◽  
Direct Methods ◽  
Uv Spectrum ◽  
Triclinic Space Group ◽  
X Ray ◽  
Bond Character

A crystal of the title compound [μ-S2{Ru(PCy3)(′S4′)}2] · 2.5 THF · 0.5 Et2O (1 · 2.5 THF · 0.5 Et2O), grown from a THF/Et2O solution, was investigated by single-crystal X-ray analysis. 1 · 2.5 THF · 0.5 Et2O crystallizes in the triclinic space group P1̄ with a = 14.209(4), b = 15.390(4), c = 19.526(6) Å, α = 111.29(2), ß = 100.43(2), γ = 95.65(2)°, and Z = 2. The crystal structure was solved by direct methods (wR2= 0.1520 for 12565 reflections; R1 = 0.0507 for 9205 observed reflections). The molecular structure of 1 · 2.5 THF · 0.5 Et2O is characterized by a trans η1 -η1-S2 bridge connecting two homochiral [Ru(PCy3)(′S4′)] fragments. The S-S bond length of 1.982(2) Å and a mean Ru-S(bridge) distance of 2.234(2) Å indicate partial double bond character of these bonds. The RuSSRu unit in 1 · 2.5 THF · 0.5 Et2O is a chromophore as indicated by its UV spectrum and can be described by a delocalized 4c-6e 7π system.

scholarly journals Crystal structure of (ethoxyethylidene)dimethylazanium ethyl sulfate

2015 ◽  
Vol 71 (12) ◽  
pp. o916-o916 ◽  
Author(s):  
Ioannis Tiritiris ◽  
Stefan Saur ◽  
Willi Kantlehner
Keyword(s):  
Crystal Structure ◽  
Double Bond ◽  
Hydrogen Bonds ◽  
Three Dimensional ◽  
Single Bond ◽  
Ethyl Sulfate ◽  
Charge Delocalization ◽  
Dimensional Network ◽  
Iminium Ion ◽  
Bond Character

In the title salt, C6H14NO+·C2H5SO4−, the C—N bond lengths in the cation are 1.2981 (14), 1.4658 (14) and 1.4707 (15) Å, indicating double- and single-bond character, respectively. The C—O bond length of 1.3157 (13) Å shows double-bond character, indicating charge delocalization within the NCO plane of the iminium ion. In the crystal, C—H...O hydrogen bonds between H atoms of the cations and O atoms of neighbouring ethyl sulfate anions are present, generating a three-dimensional network.

Sign in / Sign up

Export Citation Format

Share Document