Five-membered cyclopalladated rings: Cambridge structural database analysis of geometrical parameters and ‘aromatic’ character

1997 ◽  
pp. 75-80 ◽  
Author(s):  
Alessandra Crispini ◽  
Mauro Ghedini
Keyword(s):  
Cambridge Structural Database ◽  
Geometrical Parameters ◽  
Database Analysis ◽  
Aromatic Character ◽  
Structural Database

scholarly journals Regium Bonds between Silver(I) Pyrazolates Dinuclear Complexes and Lewis Bases (N2, OH2, NCH, SH2, NH3, PH3, CO and CNH)

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 137 ◽  
Author(s):  
Ibon Alkorta ◽  
Cristina Trujillo ◽  
Goar Sánchez-Sanz ◽  
José Elguero
Keyword(s):  
Theoretical Study ◽  
Cambridge Structural Database ◽  
Dinuclear Complexes ◽  
Chemical Shielding ◽  
Lewis Bases ◽  
Aromatic Character ◽  
Structural Database

A theoretical study and Cambridge Structural Database (CSD) search of dinuclear Ag(I) pyrazolates interactions with Lewis bases were carried out and the effect of the substituents and ligands on the structure and on the aromaticity were analyzed. A relationship between the intramolecular Ag–Ag distance and stability was found in the unsubstituted system, which indicates a destabilization at longer distances compensated by ligands upon complexation. It was also observed that the asymmetrical interaction with phosphines as ligands increases the Ag–Ag distance. This increase is dramatically higher when two simultaneous PH3 ligands are taken into account. The calculated 109Ag chemical shielding shows variation up to 1200 ppm due to the complexation. Calculations showed that six-membered rings possessed non-aromatic character while pyrazole rings do not change their aromatic character significantly upon complexation.

Crystal structures of four δ-keto esters and a Cambridge Structural Database analysis of cyano–halogen interactions

2015 ◽  
Vol 71 (10) ◽  
pp. 921-928 ◽  
Author(s):  
Kulsoom Kamal ◽  
Hardesh K. Maurya ◽  
Atul Gupta ◽  
Prema G. Vasudev
Keyword(s):  
Crystal Structures ◽  
Crystal Packing ◽  
Noncovalent Interactions ◽  
Halogen Bonding ◽  
Cambridge Structural Database ◽  
Database Analysis ◽  
Molecular Conformations ◽  
Keto Esters ◽  
Organic Molecular Crystals ◽  
Structural Database

The revived interest in halogen bonding as a tool in pharmaceutical cocrystals and drug design has indicated that cyano–halogen interactions could play an important role. The crystal structures of four closely related δ-keto esters, which differ only in the substitution at a single C atom (by H, OMe, Cl and Br), are compared, namely ethyl 2-cyano-5-oxo-5-phenyl-3-(piperidin-1-yl)pent-2-enoate, C19H22N2O3, (1), ethyl 2-cyano-5-(4-methoxyphenyl)-5-oxo-3-(piperidin-1-yl)pent-2-enoate, C20H24N2O4, (2), ethyl 5-(4-chlorophenyl)-2-cyano-5-oxo-3-(piperidin-1-yl)pent-2-enoate, C19H21ClN2O3, (3), and the previously published ethyl 5-(4-bromophenyl)-2-cyano-5-oxo-3-(piperidin-1-yl)pent-2-enoate, C19H21BrN2O3, (4) [Maurya, Vasudev & Gupta (2013).RSC Adv.3, 12955–12962]. The molecular conformations are very similar, while there are differences in the molecular assemblies. Intermolecular C—H...O hydrogen bonds are found to be the primary interactions in the crystal packing and are present in all four structures. The halogenated derivatives have additional aromatic–aromatic interactions and cyano–halogen interactions, further stabilizing the molecular packing. A database analysis of cyano–halogen interactions using the Cambridge Structural Database [CSD; Groom & Allen (2014).Angew. Chem. Int. Ed.53, 662–671] revealed that about 13% of the organic molecular crystals containing both cyano and halogen groups have cyano–halogen interactions in their packing. Three geometric parameters for the C—X...N[triple-bond]C interaction (X = F, Cl, Br or I),viz.the N...Xdistance and the C—X...N and C—N...Xangles, were analysed. The results indicate that all the short cyano–halogen contacts in the CSD can be classified as halogen bonds, which are directional noncovalent interactions.

Packing Modes in Nitrobenzene Derivatives. II. The `Pseudo-Herringbone' Mode

1997 ◽  
Vol 53 (6) ◽  
pp. 996-1005 ◽  
Author(s):  
I. André ◽  
C. Foces-Foces ◽  
F. H. Cano ◽  
M. Martinez-Ripoll
Keyword(s):  
Weak Interactions ◽  
Cambridge Structural Database ◽  
Geometrical Parameters ◽  
Acta Cryst ◽  
Structural Database

Nitrobenzene derivatives pack in two main motifs: stacks [see André , Foces-Foces, Cano & Martinez-Ripoll (1997). Acta Cryst. B53, 984–995] and `pseudo- herringbone' together account for some 61.5% of the structures classified as BCLASS = 15 by the Cambridge Structural Database. Several geometrical parameters allow the classification of the `pseudo-herringbone' category into four main motifs. Weak interactions appear to play an important role in this packing mode.

Hydration in Molecular CrystalsA Cambridge Structural Database Analysis

2003 ◽  
Vol 3 (5) ◽  
pp. 663-673 ◽  
Author(s):  
Amy L. Gillon ◽  
Neil Feeder ◽  
Roger J. Davey ◽  
Richard Storey
Keyword(s):  
Cambridge Structural Database ◽  
Database Analysis ◽  
Structural Database

Aromaticity of benzene derivatives: an exploration of the Cambridge Structural Database

2018 ◽  
Vol 74 (2) ◽  
pp. 148-151 ◽  
Author(s):  
Irena Majerz ◽  
Teresa Dziembowska
Keyword(s):  
Solid State ◽  
Harmonic Oscillator ◽  
Cambridge Structural Database ◽  
Homa Index ◽  
Benzene Derivatives ◽  
Aromatic Character ◽  
Harmonic Oscillator Model ◽  
Benzene Rings ◽  
Structural Database ◽  
Hydroxy Groups

The harmonic oscillator model of aromaticity (HOMA) index, one of the most popular aromaticity indices for solid-state benzene rings in the Cambridge Structural Database (CSD), has been analyzed. The histograms of HOMA for benzene, for benzene derivatives with one formyl, nitro, amino or hydroxy group as well as the histograms for the derivatives with two formyl, nitro, amino or hydroxy groups inortho,metaandparapositions were investigated. The majority of the substituted benzene derivatives in the CSD are characterized by a high value of HOMA, indicating fully aromatic character; however, the distribution of the HOMA value from 1 to about 0 indicates decreasing aromaticity down to non-aromatic character. Among the benzene derivatives investigated, a significant decrease in aromaticity can be related to compounds with diamino and dinitro groups in themetaposition.

Influence of ring size on the strength of carbon bonding complexes between anions and perfluorocycloalkanes

2014 ◽  
Vol 16 (36) ◽  
pp. 19192-19197 ◽  
Author(s):  
Antonio Bauzá ◽  
Tiddo J. Mooibroek ◽  
Antonio Frontera
Keyword(s):  
Ab Initio ◽  
Cambridge Structural Database ◽  
Ring Size ◽  
Database Analysis ◽  
Structural Database ◽  
High Level ◽  
Carbon Bonding

High level ab initio calculations and Cambridge Structural Database analysis were used to demonstrate the importance of carbon bonding in cyclobutane rings.

Comparative study of imidazole hydration:Ab initioand electrostatic calculations vs. Cambridge structural database analysis

1990 ◽  
Vol 11 (9) ◽  
pp. 1038-1046 ◽  
Author(s):  
Giuliano Alagona ◽  
Caterina Ghio ◽  
Péter Nagy ◽  
Kálmán Simon ◽  
Gábor Náray-Szabo
Keyword(s):  
Comparative Study ◽  
Cambridge Structural Database ◽  
Database Analysis ◽  
Structural Database ◽  
Electrostatic Calculations
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