Investigating the effect of flexible ligands on the crystal engineering of the iron(II) coordination compounds

Abstract

Iron(II) coordination compounds [Fe(bib)2(NCS)2] n (1) and [Fe(bpp)(NCS)2] (2) were synthesized by using the neutral flexible bidentate N-donor ligands 1,4-bis(imidazolyl)butane (bib) and 1,3-bis(3,5-dimethylpyrazolyl)propane (bpp), mono-anionic NCS- ligand and appropriate iron(II) salts. In the CdSO4 network structure of 1, the iron(II) ion lies on an inversion center and exhibits an FeN 6 octahedral arrangement while, in the monomeric structure of 2, the iron(II) ion adopts an FeN4 tetrahedral geometry. In the complex 1, each μ2-bib acts as bridging ligand connecting two adjacent iron(II) ions while in the complex 2, the bpp ligand is coordinated to an iron(II) ion in a cyclic-bidentate fashion forming an eight-membered metallocyclic ring. Coordination compounds 1 and 2 have been characterized by infrared spectroscopy, elemental analyses and single-crystal X-ray diffraction. Thermal analysis of polymer 1 was also studied. An attempt to synthesize [Fe(bbd)(NCS)2] (3) (bbd = 1,4-bis(3,5-dimethylpyrazolyl)butane) with the reaction of bbd, Fe(NH4)2(SO4) 2·6H2O and KNCS was failed. © 2013 Published by Elsevier B.V.