engleski

A New Heterometallic (Ni^2+ and Cr^3+) Complex – Crystal Structure and Spectroscopic Characterization

A new heterometallic complex, of the composition [Ni(bpy)(3)](2)[Cr(C2O4)(3)]NO3 center dot 10H(2)O (bpy = 2, 2'-bipyridine) (1), was synthesized and characterized by elemental and TG/DTA analyses, IR, UV/vis and EPR spectroscopy and by a single-crystal X-ray diffraction study. The compound crystallizes in the monoclinic P2(1)/c space group, with the unit cell parameters: a = 23.201(7), b = 13.562(4), c = 22.350(7) angstrom, beta = 92.782(5)degrees, V = 7024(4) angstrom(3) and Z = 4. The molecular structure of I consists of two symmetry independent [Ni(bpy)(3)](2+) cations, one [Cr(C2O4)(3)](3-) anion, one nitrate anion and 10 molecules of water. Due to the rigidity of the didentate ligands, both [Ni(bpy)(3)](2+) and [Cr(C2O4)(3)](3-) ions possess a trigonally distorted octahedral geometry. Analysis of crystal packing revealed the existence of a specific type of supramolecular contact comprising four bipyridine ligands from two neighbouring [Ni(bpy)(3)](2+) units - a quadruple aryl embrace (QAE) contact. The electronic spectrum showed superposition of bands characteristic for both nickel(II) and chromium(III) six-coordinated ions. The X-band EPR spectra were recorded on a single crystal and on a powdered sample of 1 in the temperature range 300-5 K. From the obtained spectra, the spin-Hamiltonian parameters for Cr3+ were deduced. Throughout the investigated temperature range, Ni2+ was EPR silent.

heterometallic complex ; nickel complex ; chromium complex ; crystal structure ; IR and UV/Vis spectroscopy ; EPR

Rad je prezentiran na skupu 29. European Congress on Molecular Spectroscopy, održanom od 31.08.-05.09.2008., Opatija, Hrvatska ; J. Barnes, Krešimir Furić and Svetozar Musić (ur.)