Synthesis, characterization and magnetic properties of four new organically templated metal sulfates [C5H14N2][M(II)(H2O)6](SO4)2, (M(II) = Mn, Fe, Co, Ni)

Synthesis, structural determination and antimicrobial evaluation of two novel CoII and ZnII halogenometallates as efficient catalysts for the acetalization reaction of aldehydes

Background

Complexes of imidazole derivatives with transition metal ions have attracted much attention because of their biological and pharmacological activities, such as antimicrobial, antifungal, antiallergic, antitumoural and antimetastatic properties. In addition, imidazoles occupy an important place owing to their meaningful catalytic activity in several processes, such as in hydroamination, hydrosilylation, Heck reaction and Henry reaction. In this work, we describe the crystallization of two halogenometallate based on 2-methylimidazole. Their IR, thermal analysis, catalytic properties and antibacterial activities have also been investigated.

Results

Two new isostructural organic-inorganic hybrid materials, based on 2-methyl-1H-imidazole, 1 and 2, were synthesized and fully structurally characterized. The analysis of their crystal packing reveals non-covalent interactions, including C/N–H···Cl hydrogen bonds and π···π stacking interactions, to be the main factor governing the supramolecular assembly of the crystalline complexes. The thermal decomposition of the complexes is a mono-stage process, confirmed by the three-dimensional representation of the powder diffraction patterns (TDXD). The catalytic structure exhibited promising activity using MeOH as solvent and as the unique source of acetalization. Moreover, the antimicrobial results suggested that metal-complexes exhibit significant antimicrobial activity.

Conclusion

This study highlights again the structural and the biological diversities within the field of inorganic–organic hybrids.

Crystal structure of 2-methyl-piperazine-1,4-diium bis-(hydrogen maleate)

In the title salt, C5H14N2 (2+)·2C4H3O4 (-), the asymmetric unit contains two independent 2-methyl-piperazinium dications, which comprise a racemic pair, and four hydrogen maleate monoanions. In the roughly planar hydrogen maleate anions, intra-molecular O-H⋯O hydrogen bonds generate S(7) rings. In the crystal, the four independent anions are linked to the 2-methyl-piperazinium cations through N-H⋯O hydrogen bonds, forming two-dimensional layered structures lying parallel to (001).

Inorganic layered structures in hybrid double sulfates: related phases and thermal reactivity

The crystal structures of hybrid sulfate salts show a lamellar aspect with interlayer spacings of 12 and 13 Å.

Bis(4-amino-pyridinium) hexa-aqua-nickel(II) bis-(sulfate)

In the title compound, (C₅H₇N₂)₂[Ni(H₂O)₆](SO₄)₂, the Ni^II cation is located on an inversion centre and is coordinated by six aqua ligands in a slightly distorted octa­hedral coordination environment. The [Ni(H₂O)₆]²⁺ ions are connected through an extensive network of O—H⋯O hydrogen bonds to sulfate anions, leading to the formation of layers parallel to (001). The 4-amino­pyridinium cations are located between these layers and are connected to the anionic framework by N—H⋯O hydrogen bonds. Weak π–π inter­actions between the pyridine rings, with a centroid–centroid distance of 3.754 (9) Å, provide additional stability to the crystal packing.