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With the current interest in multicomponent crystals containing chiral residues, a wide variety of studies could benefit from a comprehensive inventory of chirality in multicomponent crystals. We combined computational approaches for identifying chiral carbon atoms and methods for identifying residue types in order to make such an inventory for all organic multicomponent entries in the Cambridge Structural Database (CSD). [Groom et al., Acta Cryst. B, 2016, 72, 171–179] This inventory provides a new and extended view on multicomponent classification by including chirality. We classified 66 355 multicomponent CSD-entries into one of seven multicomponent classes and one of seven stereoisomerism classes, based on the residue type and the presence of chirality in each entry. We present refcode lists of the 49 resulting subclasses, and examples of applications of the combined classification. [ABSTRACT FROM AUTHOR]

This paper presents a way to accomodate large numbers of crystal structures, as present in e.g. the Cambridge Structural Database (CSD), in a self-organizing map. The structures are represented by their calculated powder diffraction patterns. The use of a recently introduced similarity criterion is essential: the weighted cross-correlation. This accurately reflects the similarities of the powder patterns and therefore, indirectly measures the resemblance of crystal packings. It will be shown that good results are obtained, even if the network is trained with a small subset of a complete database. This makes it possible to construct the map on common hardware in a few hours. Such a map provides several possibilities for two-dimensional visualization, but additionally has a number of important applications. Two such applications are fast and easy screening of a database, and providing an overview of the contents of a database in terms of structural diversity of specific chemical classes of compounds, e.g. steroids or peptides. A third is the selection of archetypical structures, covering the complete structural space. [ABSTRACT FROM AUTHOR]

The reaction of Cu(ClO4)2·6H2O with the new tripodal ligand HNpy2pz (N-bis[(pyridin-2-yl)methyl][1H-pyrazol-3-yl)methyl]amine) in the presence of 1 equiv of triethylamine results in the formation of a doubly pyrazotato-bridged dicopper(II) complex, [Cu(Npy2pz)]2(ClO4)2·2CH3CN (1). The crystal structure of 1 was determined by X-ray crystallography and was found to consist of two nearly identical discrete dinuclear molecules with bis(pyrazolato) bridges. The copper(II) ion has a trigonal bipyramid geometry achieved by the coordination of an aliphatic nitrogen, two pyridine moieties, and two pyrazolato nitrogens. Variable temperature-dependent magnetic data show that antiferromagnetic interactions operate in 1 as a result of the binding angle of the pyrazolato bridge. In solution, the stability of the dinuclear cation, [Cu(py2pz)]22+, is highly dependent on the concentration, as indicated by ESI-MS, ligand field, cyclic voltammetry, EPR, and ¹H NMR studies. [ABSTRACT FROM AUTHOR]

The synthesis, crystal structures, as well as the electronic and spectroscopic properties, of two new mononuclear Cu(II) isomeric compounds containing the ligand 2,2′-bi-imidazoline (biz) are reported. Both Cu(II) compounds, the blue [Cu(biz)2(ClO4)2] (1) and the violet [Cu(biz)2](ClO4)2 (2), have the same stoichiometry and but differ in the location of the perchlorate anions. The basal plane of both compounds is formed by four nitrogen atoms of two dichelating biz ligands. In compound 1, the apical position is occupied by two oxygen atoms of two perchlorate anions, resulting in an elongated octahedral geometry around the Cu ion. In compound 2, the perchlorate anions are not coordinating to the Cu ion, resulting in a square planar geometry around the Cu atom. Both isomers show different and interesting H-bonding properties. The electronic, EPR and IR spectroscopy results are in agreement with the structural geometry. In frozen solution (at 77 K) the EPR spectrum is identical for both compounds, so in that case they have both the same geometry. [Copyright &y& Elsevier]

The crystal structure of [Cu(nhep)Cl]2 (Hnhep=1-(2-hydroxyethyl)-pyrazole) shows both copper(II) ions to be in a slightly distorted square-planar CuO2NCl environment with the copper(II) ions bridged by the oxygen atoms of the dehydronated ligands. The Cu2O2 core has an asymmetric geometry with a Cu…Cu distance of 3.055 A˚. The EPR and magnetic susceptibility measurements indicate the presence of a very strong antiferromagnetic coupling between the copper ions, which results in essential diamagnetic behavior. [Copyright &y& Elsevier]