A new bis(oxalato)chromate(III) salt: synthesis, crystal structure, thermal behavior and magnetic properties of (C3H5N2)[Cr(C2O4)2(H2O)2].2H2O

Abstract

A new chromium(III) salt (C3H5N2)[Cr(C2O4)2(H2O)2].2H2O, trans-diaquabis(oxalato) chromate(III) imidazolium dihydrate, has been synthesized and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic system, C2/c space group with a = 10.836(1)Å, b = 7.541(1)Å, c = 16.349(3)Å and β = 93.52(1)°. The structure of the title compound consists of [Cr(C2O4)2(H2O)2]− mononuclear anions, imidazolium cations and uncoordinated water molecules. The crystal structure data indicates that the Cr +III ion is six coordinated in a distorted octahedral geometry, with four equatorial O atoms of two oxalate anions acting as chelating ligands and two axial O atoms from two water molecules. Structural cohesion is established by intermolecular O–H…O hydrogen bonds connecting the ionic entities and water molecules. In fact, both coordinated and uncoordinated water molecules play an important role in the hydrogen-bonded system, stabilizing the structure. Magnetic susceptibility measurements of the title compound in the range 2-300K exhibit paramagnetic behavior at high temperature. However, at low temperature, the magnetic data show the occurrence of weak antiferromagnetic intermolecular interactions between the local spin.