Synthesis, spectroscopic and structural investigation of two nickel(II) thiocyanate complexes with isonicotinic acid

Abstract

Two co-crystals of trans-[Ni(NCS) 2(H 2O) 2(isonicH) 2] with isonicotinic acid and water molecules (isonicH = isonicotinic acid, i.e., pyridine-4-carboxylic acid) were obtained by reaction of Ni(NO 3) 2·6H 2O, isonicH and KSCN in 1:2:2 molar ratio in aqueous media. One co-crystal [Ni(NCS) 2(H 2O) 2(isonicH) 2] 2·4(isonicH)·3(H 2O) ( 2), is obtained from reaction which has been performed at room temperature while the other one, [Ni(NCS) 2(H 2O) 2(isonicH) 2]·(isonicH)·2(H 2O) ( 1), was obtained by refluxing the reaction mixture for a few hours. The complexes are characterized by IR-spectroscopy and thermal and X-ray crystallographic methods. The compounds crystallize in monoclinic C2/ c ( 1) and P2 1/ c ( 2) space groups and in both complexes N 4O 2 nearly perfect octahedron around nickel is established. In both compounds molecules are linked into three-dimensional framework by O–H⋯O, N–H⋯O and O–H⋯S hydrogen bonds. The co-crystallized isonicotinic acid molecules are mutually linked forming C 2 1(7)[R 2 1(4)] ( 1) and in C(7) ( 2) hydrogen-bond motifs along b axis. The IR and thermal data correlate with the structures of the complexes in the solid state.