Pressure-Induced Spin Transition of [FeII(H2O)2(PTZ)2] Complex : Characterization by Powder X-ray Diffraction, Raman and X-Ray Absorption Spectroscopy

• Main Authors: Jia-Ze Wang, 王家澤
• Other Authors: I-Jui Hsu
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/tx7g5w

碩士 === 國立臺北科技大學 === 有機高分子研究所 === 101 === An iron(II) complex, [FeII(H2O)2(PTZ)2] (PTZ = 5-(2-Pyridyl)-1H-tetrazole), was synthesized and characterized by powder X-ray diffraction, X-ray absorption spectroscopy (XAS), magnetic susceptibility, and Raman spectroscopy. The Rietveld refinement confirms Fe is at inversion center bonded by four N atoms of PTZ ligands at equatorial positions and two O atoms of H2O at axial sites. The averaged bond lengths of Fe-N and Fe-O are 2.16(1) and 2.15(1) A, respectively. The magnetic measurement and Fe L2,3 –edges XAS indicate that it is at high spin (HS) state with four unpaired electrons (Stotal = 2) and the crystal field strength (10Dq) is about 1.0 eV at ambient. In pressure induced experiment, the compound transitions to low spin (LS) state around 7.1GPa and the averaged bond lengths of Fe-N and Fe-O are 1.95(2) and 1.94(2) A, respectively, based on EXAFS (extended x-ray absorption fine structure) analysis. According to X-ray diffraction measurements, the phase transition pressure is around 4.65GPa indicated by the disappearance of reflection (1 1 0) .This is the direction of both PTZ ligands can move toward together. Such pressure induced HS to LS transitions is reversible and confirmed by Fe K-edge XANES (X-ray absorption near edge structure), powder X-ray diffraction and Raman measurement.