Perla Elizondo

Diaqua­tris­(nitrato-κ2O,O′){2,2′-[pyridine-2,6-diylbis(methyl­ene­oxy)]dibenzaldehyde-κO1}dysprosium(III)–2,2′-[pyridine-2,6-diylbis(methyl­ene­oxy)]dibenzaldehyde (1/1)

The title compound, [Dy(NO3)3(C21H17NO4)(H2O)2]·C21H17NO4, may be considered as an organic–metalorganic 1:1 co-crystal, in which the two dialdehyde molecules act as a ligand and as an organic moiety, respectively. The DyIII atom coordinates nine O atoms from the organic ligand, bidentate nitrate ions and water molecules, approximating a square-face-tricapped trigonal–prismatic geometry. The coordinated dialdehyde is not planar: the uncoordinated oxybenzaldehyde group is twisted by 39.96 (4)° from the rest of the ligand. In contrast, the free organic moiety is almost planar, with an r.m.s. deviation of 0.15 Å. In the crystal, segregated stacks of dialdehyde are formed in the [100] direction. For the complex, the shortest π–π contact is found at 3.781 (2) Å, and for the free ligand, at 3.785 (2) Å. The crystal structure is further stabilized by O—H⋯O and O—H⋯N hydrogen bonds in which coordinated water molecules are the donor groups.

N,N′,N′′-Tris(2-nitro­benz­yl)-2,2′,2′′-nitrilo­triethan­aminium trichloride 1.41-hydrate

The title compound, C27H36N7O6 3+·3Cl−1.41H2O, is the hydrochloride of a tripodal amine, and was structurally characterized because the free base, used as a ligand in podate complexes, is an oily material. In the cation, the secondary amine groups are protonated, and, despite the induced Coulombic repulsions, a claw-like conformation is stabilized, with a cavity approximating C 3 point symmetry. Such a topology, with the lone pair of the tertiary N atom placed inside the cavity, allows the encapsulation of guest species. Indeed, three chloride counter-ions balance the charges, one of which is located inside the cation cavity and is strongly bonded to the NH2 + groups. The asymmetric unit is completed by two water molecules with occupancies 0.793 (11) and 0.621 (9). The crystal structure is formed by a complex network of efficient N—H⋯Cl and O—H⋯Cl hydrogen bonds. One nitro group also forms weak contacts with a water molecule.

1,4-Bis(2-nitro­phen­oxy)butane

The asymmetric unit of the title compound, C16H16N2O6, contains one-half molecule, the mid-point of the central C—C bond being located on a crystallographic inversion center. The crystal structure shows weak interactions between the O atoms of the nitro groups and two different C—H groups of the benzene rings. The extended weak hydrogen-bond formation, involving the NO2 groups, generates an infinite three-dimensional network.