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Two copper complex solvatomorphs, namely (3,10-C-meso-3,5,7,7,10,12,14,14-octa­methyl-1,4,8,11-tetra­aza­cyclo­tetradecane)bis­(perchlorato-[kappa]O)copper(II) 1.2-hydrate, [Cu(ClO4)2(C18H40N4)]·1.2H2O, (I), and (3,10-C-meso-3,5,7,7,10,12,14,14-octa­methyl-1,4,8,11-tetra­aza­cyclo­tetradecane)bis­(perchlor­ato-[kappa]O)copper(II), [Cu(ClO4)2(C18H40N4)], (II), are described and compared with each other and with a third, already reported, anhydrous diastereomer, denoted (III). Both compounds present very similar centrosymmetic coordination environments, with the CuII cation lying on an inversion centre in a distorted 4+2 octa­hedral environment, defined by the macrocyclic N4 group in the equatorial sites and two perchlorate groups in trans-axial positions [one of the perchlorate ligands in (I) is partially disordered]. The most significant difference in mol­ecular shape is seen in the orientation of the perchlorate anions, and the influence of this on the intra­molecular hydrogen bonding is discussed. The (partially) hydrated state of (I) favours the formation of chains along [011], while the anhydrous character of (II) and (III) promotes loosely bound structures with low packing indices.

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The isomorphous title compounds, [Tr(S4O6)(C12H12N2)2]·2C3H7NO (Tr = CdII and ZnII), consist of metal centres to which one tetra­thio­nate and two 4,4′-dimethyl-2,2′-bi­pyridine chelating ligands bind. The structures are completed by two symmetry-related di­methyl­formamide solvent mol­ecules. Each metal-centred complex is bis­ected by a twofold axis running through the metal centre and halving the chelating tetra­thio­nate dianion through the central S—S bond. The ancillary symmetry-related 4,4′-dimethyl-2,2′-bi­pyridine lig­ands act as chelates. This results in a distorted six-coordinate geometry, with similar Tr—O/N distances but central angles differing substanti­ally from 90 and 180°. Both ligands are basically featureless from a geometric point of view, with torsion angles in both coordinated tetra­thio­nate groups suggesting a trend linking metal size (covalent radius) and ligand `openness'. Packing is directed by (C—H)aromatic...O bridges and π–π offset stacked inter­actions defining chains along [001], further linked by weaker (C—H)methyl...O bridges, some of them mediated by the di­methyl­formamide solvent mol­ecules.

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The natural title compound, C11H12O4, extracted from the Chilean native tree Aristotelia chilensis (Maqui), is a polymorph of the synthetic E form reported by Xia, Hu & Rao [Acta Cryst. (2004), E60, o913-o914]. Both rotational conformers are identical from a metrical point of view, and only differ in the orientation of the 3,4-dihydroxyphenyl ring with respect to the rest of the molecule, which leads to completely different crystal structure arrangements and packing efficiencies. The reasons behind both reside in the different hydrogen-bonding inter­actions.
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