Blanca Nájera

A NEW EXPANDED SCHIFF-BASE CRYPTAND

Abstract A new expanded Schiff-base cryptand derived from the direct ‘2 + 3′ cyclocondensation of tris(2-aminoethyl)amine (tren) and 2,6-bis[formylphenoxymethyl]-pyridine (bfpp) is reported with its dinuclear copper (II) perchlorate complex. Reaction of tren and bfpp in the same ratio and in the presence of metal templates gave metal complexes of ‘1 + 1’ and ‘2 + 2’ macrocycles bearing one and two aminoethyl pendant arms, respectively.

The interaction of AgI, ZnII and PbII with a pyridinyl-derived n5-macrocycle

The interaction of AgI, ZnII and PbII with the macrocycle L1 containing an N5-donor set has been investigated. The 1H nuclear magnetic resonance spectra of the complexes showed broad peaks, suggesting a slow exchange of metal ions between complexed and uncomplexed sites. The 1 : 1 (metal : ligand) stoichiometry was confirmed by first atom bombardment mass spectrometry and elemental microanalysis, solvent molecules being included when suggested by the infrared spectra. The X-ray crystal structures of [AgL1]ClO4, [ZnL1](ClO4)2 and [PbL1(NO3)2] have been determined. The metal atoms in complexes are endomacrocyclic with the silver atom and zinc atom in a pentacoordinate environment comprising the ligand N5-donor set. The lead atom prefers seven coordination derived from the full donor set of the macrocycle and two oxygens from dinitrate anions.

Synthesis and crystal structure of a macrocyclic complex precursor: Bis-(2-amino-1-methyliminobenzene)1,2-ethane nickel(II) dichloride

NiLCIl2 (L = bis-(2-amino-1-methyliminobenzene)1,2-ethane) crystallizes in space group P-1 with a = 9.042(2), b = 10.263(10), c = 11.045(2) Å, α = 94.76(10), β = 108.30(10), γ = 109.86(10)°, Z = 2, and represents a precursor of a tetradentate azamacrocyclic complex. The structure is stabilized by a system of intramolecular and intermolecular H-bonding involving chloride ions and nitrogen atoms. The coordination geometry about nickel(II) is slightly distorted octahedral.

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.

The X-Ray Crystal Structures of Two Derivatives of2,6-Bis{[2-(dimethoxymethyl)phenoxy]methyl}pyridine

The X-ray crystal structures of 2,6-bis{[2-dimethoxymethyl)phenoxy]methyl}pyridine and 2,6-bis{[2-(hydroxymethyl)-phenoxy]methyl}pyridine are reported.