Synthesis and Crystal Structures of Two Complexes with Carboxylic Derivatives of Nitrogen-containing Heterocycle Ligands

AbstractTwo new complexes [Zn(pcn) 2 (H 2 O) 2 ] (1) and [Cd(inic) 2 (H 2 O) 4 ] (2) (pcn = 2-pyrazinecarboxylate, inic = isonicotinic acid) were synthesized by the hydrothermal reaction and characterized by single crystal X-ray diffraction, elemental analysis, IR spectrum and UV spectrum. In complex 1, the Zn(II) central ion is six-coordinated by two oxygen atoms and two nitrogen atoms from pcn ligands and two oxygen atoms from two coordinated water molecules. In complex 2, the Cd(II) central ion is six-coordinated by two nitrogen atoms from isonicotinate ligands and four oxygen atoms from the coordinated water molecules. Both complexes are mononuclear but hydrogen bonds enrich the structural construction. The visible spectra of the complexes between 200 and 300 nm are assigned to intraligand (IL) π-π* transitions of the pyridyl or pyrazine ligands.Graphical AbstractThe geometry around the Cd(II) ion may be described as slightly distorted octahedron with two nitrogen atoms of isonicotinate (N, N0A), four oxygen atoms of the coordinating water molecules O1, O1A, O2 and O2A. In the complex, atoms O1, O1A, O2 and O2A form the equatorial plane around Cd (II) and the axial positions are occupied by N and N0A. The cadmium ion lies in the plane and the angles of N(1)-Cd-N(0A), O(1)-Cd-O(1A) and O(2)-Cd-O(2A) are all 180.00°. The isonicotinate acts as a monodentate donor via pyridine nitrogen. The datas of bond lengths and the associated angles indicate that Cd(II) is located in a distorted octahedral coordination environment.[IMAGE]