PROPRIEDADES VIBRACIONAIS DO CRISTAL DE Ni(II)(L-TREONINA)2(H2O)2 EM TEMPERATURA AMBIENTE E EM FUNÇÃO DA TEMPERATURA

Abstract

In this work, we synthesize and characterize the Ni(II)(L-threonine)2(H2O)2 crystal. Ni(II)(L-threonine)2(H2O)2 single crystals were grown by the slow evaporation method, and L-threonine must be anionically shaped to have proper crystal growth, the duration was a maximum of one month until the first crystals appeared, then the sample was characterized by the X-ray diffraction (XRD) technique in which the Rietveld refinement to determine material structure. The XRD analysis and Rietveld method confirmed that the Ni(L-threonine)2 complex crystallizes in the orthorhombic form of space group C2221, Z = 8, with the lattice parameters a = 5.7645 Å, b = 10, 1483(2) Å, c = 22, 2144(5) Å, with volume V = 1299.54(4) Å3 . The crystal was also subjected to Raman spectroscopy analysis, where the behavior of the phonons at room temperature was studied, with the following polarizations: X(YY)X, X(YZ)X, Y(XX)Y, Y(XZ )Y, Y(ZZ)Y, Z(XX)Z, Z(XY)Z and Z(YY)Z, whereupon was observed, according to vibrational modes, that the crystalline structure of this complex has a stable behavior, that is , the modes coincide in parallel polarizations. Thus, only two polarizations were chosen for assignment analysis of these modes, being Z(XX)Z and Z(XY)Z. we was also performed computational computation via density functional theory (DFT), in order to assist in the assignment of vibrational modes, where it was evident the types of vibrations that occur between atomic bonds, especially those involving the nickel atom. The results, at low temperatures, showed that most vibrational modes follow the natural tendency of the phonos (displacement to higher energies with decreasing temperature).