Structural aspects and solution behavior of metallosupramolecular compound of FeIII ion obtained by proton transfer

Pyridine-2,6-dicarboxylates in monomeric iron complexes – structural aspects

This review includes 70 monomeric high-spin complexes of the following general compositions: [Fe(II)(η3-pdc)(L)3], [Fe(III)(η3-pdc)(L)3]+, [Fe(II)(η3-pdc)2]2− and [Fe(III)(η3-pdc)2]− (pdc = pyridine-2,6-dicarboxylate (−2)). Each Fe(II) atom has a distorted octahedral geometry. The Fe(III) atoms have a distorted octahedral geometry (most common) and in some examples have a distorted pentagonal-bipyramidal geometry. The chelating donor ligands create varieties of n-membered metallocyclic rings: ONO, OCO, NC2N, OC2N, OC2NO and OC3O. Some cooperative effects between Fe(II) and Fe(III) complexes were found and discussed. There are complexes that are examples of distortion isomerism.

Bis(9-aminoacridinium) bis(pyridine-2,6-dicarboxylato)zincate(II) trihydrate

In the title compound, (C13H11N2)2[Zn(C7H3NO4)2]·3H2O, the ZnIIion is six-coordinated with the N4O2donor set being a distorted octahedron through two almost perpendicular (r.m.s. deviation of ligand atoms from the mean plane is 0.057 Å) tridentate pyridine-2,6-dicarboxylate ligands [dihedral angle between the ligands = 86.06 (4)°]. The charge is compensated by two 9-aminoacridinium cations protonated on the ring N atom. A variety of intermolecular contacts, such as ion–ion, N—H...O and O—H...O hydrogen bonds, and π–π stacking [centroid–centroid distances = 3.4907 (9)–4.1128 (8) Å], between cations and between anions, play important roles in the formation of the three-dimensional network.

Poly[(μ2-2-aminopyrimidine-κ2N1:N3)di-μ2-chlorido-mercury(II)]

The title compound, [HgCl₂(C₄H₅N₃)]_n, features a two-dimensional network parallel to (001) that is based on an Hg^II atom octahedrally coordinated by four μ₂-Cl atoms and two μ₂-2-amino­pyrimidine (apym) ligands in trans positions, yielding a distorted HgCl₄N₂ octa­hedron. The coordination network can be described as an uninodal 4-connected net with the sql topology. The Hg^II ion lies on a site of -1 symmetry and the apym ligand lies on sites of m symmetry with the mirror plane perpendicular to the pyrimidine plane and passing through the NH₂ group N atom. This polymeric structure is stabilized by N—H⋯Cl hydrogen bonds and columnar π–π stacking of pyrimidine rings, with a centroid–centroid distance of 3.832 (2) Å.

2-Amino-pyridinium bis-(pyridine-2,6-dicarboxyl-ato)ferrate(III)

In the title compound, (C(5)H(7)N(2))[Fe(C(7)H(3)NO(4))(2)] or [2-apyH][Fe(pydc)(2)], the asymmetric unit contains an [Fe(pydc)(2)](-) (pydc is pyridine-2,6-dicarboxyl-ate) anion and a protonated 2-amino-pyridine cation ([2-apyH](+)). The complex anion contains an Fe(III) atom within a distorted octahedral FeN(2)O(4) coordination geometry. N-H⋯O and C-H⋯O hydrogen bonding, offset π-π stacking [centroid-centroid distance = 3.805 (13) Å] and C=O⋯π inter-actions [3.494 (14) Å] generate a three-dimensional network structure.