An X-ray study of new hybrid systems of Fe(III) and Cu(II) based anions

Organic-inorganic hybrid compounds represent one of the most important developments in materials chemistry in recent years [1]. The role of weak intermolecular interactions in the stabilization of these hybrid systems is one of the main targets of our investigation in crystal engineering study. In continuation of our research on N-aromatic heterocyclic-metal halide salts, the X-ray crystal structures of 4-dimethylaminopyridinium (HDMAP) cation with tetrachlorocuprate (II) (1) and tetrachloroferrate (III) (2) anions is reported [2,3]. In (1), Cu(II) is situated on a twofold rotation axis (4 e). The [CuCl4]2- ions are highly distorted with a mean trans angle of 141.02(1)⁰ as a result of hydrogen bonding interactions with two nearly planar HDMAP cations (0.0295 Å mean deviation). The crystal structure of (1) is stabilized by N–H...Cl and C–H...Cl hydrogen bonds. In the three dimensional network, cations and anions pack in the lattice so as to generate chains of [CuCl4]2- anions separated by two orientations of cation layers, which are interlocked through π–π tacking contacts between pairs of pyridine rings, with centroid–centroid distances of 3.7874 (7) Å. In (2), the protonoted 4-(dimethylamino) pyridine cation is essentially planar (the r.m.s deviation for all non-H atoms being 0.004 Å). The packing of the ionic entities is realized by alternating layers of cations and [FeCl4]- anions parallel to (010) whereby the cations are oriented in a zig-zag fashion. The crystal packing is stabilized by N–H...Cl and C–H...Cl hydrogen bonds forming a three-dimensional network.

Crystal structure and hydrogen bonded network of new cadmium hybrid complex

Cadmium complexes exhibit extensive potential applications in many fields, such as magnetism materials, biological active materials, optical device and catalysis materials [1]. The reported compound [Tetrakis(5-amino-3-carboxy-1H-1,2,4-triazol-4-ium) hexachloridocadmate (II) tetrahydrate (1) ] was prepared as part of our ongoing investigations of hydrogen-bonding interactions in the crystal structures of metal-protonated N-aromatic heterocyclic hybrid frameworks [2]. 5-Amino-1H-1,2,4-triazole-3-carboxylic acid arises as a promising ligand which can be employed in the preparation of coordination compounds as a consequence of its multiple buildings sites and its basic nitrogen capable of associating with a proton H+ in acid solution [3]. The single-crystal X-ray structure analysis revealed that (1) crystallizes in the monoclinic P-1 space group, the Cd(II) atom is located at a crystallographic inversion centre. The latter ion is octahedrally coordinated by six chloride anions, Due to the presence of a considerable number of proton donors and acceptors, the crystal structure is rich in hydrogen bonding interactions which led to the formation of discrete cation layers spaced by hexachloridocadmate anions. Examination of the cation-anion interactions reveals that N-H...Cl hydrogen bonding are the major packing interactions, It appears that the layered structure results from the octahedral [CdCl6]2- anions along with its ability to form hydrogen bonds in different directions, intermolecular hydrogen bonding interactions between the chloride atom and oxygen atoms of water molecules interconnect the layers into a three-dimensional framework.