SYNTHESIS AND STRUCTURE OF IRON(III) COMPLEX WITH 2-ACETYLPYRIDINE-AMINOGUANIDINE

Schiff bases represent an interesting class of compounds due to a wide range of possible applications, especially their biological activity. Having in mind that the biological activity of the ligand could be closely related to its coordinating properties, we examined the synthesis and structure of a novel Fe(III) complex with the Schiff base of aminoguanidine and 2-acetylpyridine. Bis(ligand) complex of iron(III), of the formula [Fe(L–H)2]2(NCS)Cl, was obtained by the reaction of FeCl3 and the thiocyanate ligand salt in a mole ratio 1:1 in the presence of lithium-acetate as a deprotonating agent. The complex is obtained in the form of brown single crystals and is characterized by elemental analysis data, conductometric measurements, IR spectra, and X-ray analysis. The latter revealed that the chelating ligand is coordinated in its monoanionic form via pyridine, azomethine, and nitrogen atoms of the aminoguanidine fragment, forming octahedral environment.

Crystal and molecular structures of a binuclear mixed ligand complex of silver(I) with thiocyanate and 1H-1,2,4-triazole-5(4H)-thione

The complete molecule of the binuclear title complex, bis[μ-1H-1,2,4-triazole-5(4H)-thione-κ2 S:S]bis{(thiocyanato-κS)[1H-1,2,4-triazole-5(4H)-thione-κS]silver(I)}, [Ag2(SCN)2(C2H3N3S)4], is generated by crystallographic inversion symmetry. The independent triazole-3-thione ligands employ the exocyclic-S atoms exclusively in coordination. One acts as a terminal S-ligand and the other in a bidentate (μ2) bridging mode to provide a link between two AgI centres. Each AgI atom is also coordinated by a terminal S-bound thiocyanate ligand, resulting in a distorted AgS4 tetrahedral coordination geometry. An intramolecular N—H...S(thiocyanate) hydrogen bond is noted. In the crystal, amine-N—H...S(thione), N—H...N(triazolyl) and N—H...N(thiocyanate) hydrogen bonds give rise to a three-dimensional architecture. The packing is consolidated by triazolyl-C—H...S(thiocyanate), triazolyl-C—H...N(thiocyanate) and S...S [3.2463 (9) Å] interactions as well as face-to-face π–π stacking between the independent triazolyl rings [inter-centroid separation = 3.4444 (15) Å]. An analysis of the calculated Hirshfeld surfaces shows the three major contributors are due to N...H/H...N, S...H/H...S and C...H/H...C contacts, at 35.8, 19.4 and 12.7%, respectively; H...H contacts contribute only 7.6% to the overall surface.

(Thiocyanato-κS)tris(triphenylphosphane-κP)silver(I)

In the mononuclear title complex, [Ag(SCN)(C18H15P)3], the AgIcenter is in a slightly distorted tetrahedral coordination geometry formed by one S atom from a terminal thiocyanate ligand and three P atoms from three triphenylphosphane ligands. In the crystal, weak C—H...N hydrogen bonds connect molecules into a two-dimensional network parallel to (10\overline{1}). One of the phenyl rings is disordered over two positions which were refined with an occupancy ratio of 0.715 (16):0.285 (16).

Crystal structure of bis(3,5-dimethylpyridine-κN)bis(methanol-κO)bis(thiocyanato-κN)cobalt(II)

The asymmetric unit of the title complex, [Co(NCS)2(C7H9N)2(CH3OH)2], comprises of one CoIIcation located on a centre of inversion, one thiocyanate ligand, one methanol ligand and one 3,5-dimethylpyridine ligand. The CoIIcation is octahedrally coordinated by two terminal N-bonding thiocyanate anions, two methanol molecules and two 3,5-dimethylpyridine ligands into a discrete complex. The complex molecules are linked by intermolecular O—H...S hydrogen bonding into chains that elongate in the direction parallel to thebaxis.