Structure Correlation and Chemistry

Abstract

The main goal of crystal and molecular structure determination is to provide a starting point for understanding the physical, chemical and biological properties of matter. At present, results from nearly 300 000 crystal structure studies are available in computer-readable form. Structure correlation attempts to extract knowledge and understanding from this body of information, which is not available from its parts. This article reviews some typical examples: libraries of prototypal molecular dimensions, mappings of chemical reaction pathways, correlations between structure on one hand and energy, reaction rate, catalytic activity or magnetism on the other. The knowledge gained from structure-correlation studies, together with quantum-chemical and other modeling techniques, provides conceptual and practical tools for designing molecules and materials with tailormade properties.

Ab Initio Calculations on Bismuth Cluster Polycations

“…This small difference in total energy is also found in calculations on other nine-atom clusters, for example, Si 9 4À . [25] Such a small difference can be easily compensated for in the solid state by packing effects (which can be larger by at least one order of magnitude [31] ), since from the point of packing with counterions the D 3h cation is more ªsphericalº than C 4v and, hence, more energetically favorable. All this means that the deviation of the Bi 9 5 geometry from the one predicted by Wades rules could be accounted for by the crystal field effects rather than an intrinsic property of its electronic structure.…”

(1R,2S,5R)-2-Isopropyl-5-methylcyclohexyl 4-Aminobutyrate Hydrochloride

“…The positive charge of the cation is localized on the amino group as indicated by three hydrogen atoms that were found from the electron density difference map; in addition, this fact is proved by elongation of N1-C14 bond to 1.486(4) Å compared with the average value of 1.469 Å [6]. The title compound crystallizes in non-centrosymmetric space group indicating the presence of only Figure 1.…”

“…Boc-protected GABA was not obtained commercially and has been synthesized according to the literature procedure [8]. Structure of the obtained compound was established by 1 H-NMR spectroscopy on a AVANCE DRX 500 (500 MHz) instrument (Bruker, Davis, CA, USA) and by 13 C-NMR spectroscopy on Varian-Mercury 400 spectrometer (Varian Inc., Palo Alto, CA, USA) using DMSO-d 6 as a solvent and TMS as an internal standard. FAB mass spectrum was obtained on a VG 70-70EQ mass spectrometer (VG Analytical Ltd., Manchester, UK) equipped with Xe ion gun (8 kV); the sample was mixed with m-nitrobenzyl-alcohol matrix.…”

Novel rearrangement in the reaction of 5-methyl-5Hiso-indolo [2,1-a]benzimidazole with maleimide derivatives. Stereochemical and X-ray structural study

“…and is therefore lengthened to 1.351 Å, while a standard double bond length is 1.322 Å. 6 Apparently, this is due to the steric hindrances around the double bond. To explain this unexpected reaction we propose below a probable mechanism.…”