Nancy Pérez Rodríguez

N,N′-Bis(2-amino­benz­yl)ethane-1,2-diaminium dinitrate

In the title salt, C16H24N4 2+·2NO3 −, both the cation and anion are placed in general positions, although the cation displays non-crystallographic inversion symmetry, with the aliphatic chain extended in an all-trans conformation. The benzene rings are almost parallel, with a dihedral angle between their mean planes of 3.3 (6)°. The nitrate ions are placed in the vicinity of the protonated amine groups, forming efficient N—H⋯O inter-ion hydrogen bonds. Each nitrate ion in the asymmetric unit bridges two symmetry-related cations, forming an R 4 4(18) ring, a common motif in organic ammonium nitrate salts. This results in the formation of chains along [010] with alternating cations and anions. The neutral amine groups are involved in slightly weaker N—H⋯O hydrogen bonds with the nitrate O atoms, and there are also a number of C—H⋯O hydrogen bonds present. The resulting supramolecular structure is based on a two-dimensional network extending in the ab plane.

Tris[2-(2H-indazol-2-yl)eth-yl]amine.

The title tertiary amine, C27H27N7, a potential tripodal ligand for coordination chemistry, crystallizes with the central N atom located on a threefold axis of a trigonal cell. The gauche conformation of the N(amime)—CH2—CH2—N(indazole) chain [torsion angle = −64.2 (2)°] places the pendant 2H-indazole heterocycles surrounding the symmetry axis, affording a claw-like shaped molecule. Two symmetry-related indazole planes in the molecule make an acute angle of 60.39 (4)°. The lone pair of the tertiary N atom is located inside the cavity, and should thus be inactive (as a ligand). In the crystal, neither significant π–π nor C—H⋯π interactions between molecules are found.

N,N′-Bis(2-aza­niumylbenz­yl)ethane-1,2-diaminium tetra­chloride

The title compound, C16H26N4 4+·4Cl−, is based on a fully protonated tetraamine. In the cation, both benzene rings are connected by an all-trans chain, and the rings are almost parallel, with an angle between the mean planes of 8.34 (12)°. The benzene rings are arranged in such a way that the NH3 + substituents are oriented cis with respect to the central chain. This arrangement is a consequence of multiple N—H⋯Cl hydrogen bonds, involving all N—H groups in the cation and the four independent Cl− anions. These contacts have strengths ranging from weak to strong (based on H⋯Cl separations), and generate a complex three-dimensional crystal structure with no preferential crystallographic orientation for the contacts.

Tris{2-[(2-amino­benzyl­idene)amino]­ethyl}amine

The title Schiff base, C27H33N7, is a tripodal amine displaying C 3 symmetry, with the central tertiary N atom lying on the threefold crystallographic axis. The N—CH2—CH2—N conformation of the pendant arms is gauche [torsion angle = 76.1 (3)°], which results in a claw-like molecule, with the terminal aniline groups wrapped around the symmetry axis. The lone pair of the apical N atom is clearly oriented inwards towards the cavity, and should thus be chemically inactive. The amine NH2 substituents lie in the plane of the benzene ring to which they are bonded. With such an arrangement, one amine H atom forms an S(6) motif through a weak N—H⋯N hydrogen bond with the imine N atom, while the other is engaged in an intermolecular N—H⋯π contact involving the benzene ring of a neighbouring molecule related by inversion. The benzene rings also participate in an intramolecular C—H⋯π contact of similar strength. In the crystal structure, molecules are separated by empty voids (ca 5% of the crystal volume), although the crystal seems to be unsolvated.

Determination of the Solubility of Copper with Three Commercial Ligands and One Novel Ligand in Supercritical CO2

The solubility of four copper ligand systems in supercritical (SC) CO2 was studied. Three of the ligand systems studied were commercial ligands, while the last one was a new Schiff base reduced macrocyclic ligand. The three commercial ligands were ethylenediaminetetraacetic acid (EDTA), diisooctylphosphinic acid (DiOPA), and the anion-exchanger Aliquat 336 (methyltrioctylammonium chloride). The Schiff base reduced macrocyclic ligand was 3,6,9,12-tetraaza-4(1,2),11(1,2)-dibenzena-1(1,3)-pyridinacyclotridecaphane (TeDiPyDeca), which forms a very stable 1 + 1 copper complex (Keq = 2.42 × 106). This article presents the synthesis, Fourier transform infrared spectroscopy (FT-IR) studies, and crystal structure of the new copper complex Cu(TeDiPyDeca) as well as experimental data of solubility fitting with a Peng Robinson equation and van der Waals mixing rules. The molar volume of the solid (Vs), the vapor pressure (Pvap), and the binary interaction coefficient (k ij ) of the four metal complexes were found. The physical effects of the molecular forms of the studied copper complexes were the most important factors in regard to solubility in SC CO2.

2,2'-(Propane-1,3-di-yl)bis-(2H-indazole).

The title molecule, C17H16N4, is a bis-indazole crystallized in the rare 2H-tautomeric form. Indazole heterocycles are connected by a propane C3 chain, and the molecule is placed on a general position, in contrast to the analogous compound with a central C2 ethane bridge, which was previously found to be placed on an inversion center in the same space group. In the title molecule, indazole rings make a dihedral angle of 60.11 (7)°, and the bridging alkyl chain displays a trans conformation, resulting in a W-shaped molecule. In the crystal, molecules interact weakly through π–π contacts between inversion-related pyrazole rings, with a centroid–centroid separation of 3.746 (2) Å.