2026-09-20T08:51:05Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/70382 2023-07-11 col_2142_5131 col_2142_14789 com_2142_5130 com_2142_14788 com_2142_8903

Xie, Chuan-Liang 2014-12-15T23:19:03Z 2014-12-15T23:19:03Z 10000-01-01 1987 1987 The work described in this dissertation is directed at a better understanding of the dynamics and mechanism of the so-called spin-crossover phenomenon. Several iron spin-crossover systems, including ferrous and ferric complexes, are investigated with various spectroscopic techniques and single-crystal X-ray structure determination. In the first part the cooperativity of ferric spin-crossover complexes in the solid state and the influence of lattice solvation and metal dilution upon these properties is studied. The complex Fe(3-OMeSalAPA)$\sb 2$ClO$\sb 4$, where 3-OMeSalAPA is the Schiff base ligand condensed from one mole of 3-methoxylsalicylaldehyde with N-aminopropylaziridine, and its various halobenzene solvated forms were studied with $\sp{57}$Fe Mossbauer and EPR spectroscopies, as well as magnetic susceptibility, DSC, single-crystal structure determination and variable temperature XRD techniques. It has been found from the experimental results that the ferric complex Fe(3-OMeSalAPA)$\sb 2$ClO$\sb 4$ and its solvated forms are spin-crossover systems of the gradual type. In the second part of this thesis, an investigation of the correlation between the onset of solvate molecule dynamics and the spin-crossover phase transition is investigated. The complex Fe(dppen)$\sb 2$Cl$\sb 2$ with lattice solvate molecules of CH$\sb 3$COCH$\sb 3$, CD$\sb 3$COCD$\sb 3$, CH$\sb 2$Cl$\sb 2$, CD$\sb 2$Cl$\sb 2$, CHCl$\sb 3$, CDCl$\sb 3$ were investigated by the variable-temperature solid-state $\sp{2}$H NMR technique. Dppen stands for cis-1,2-bis(diphenylphosphano)ethylene. In the third part of this thesis, an investigation on the dynamics of the spin-state interconversion in solution and other media is presented. The spin-state interconversion rate of the ferrous complexes series (Fe(6-Me-py)$\sb{\rm n}$(py)$\sb{\rm 3-n}$tren) (ClO$\sb 4)\sb 2$ (n = 0,1,2,3), where the ligand is the Schiff base of triethylaminotetraamine(tren) was measured by the means of the laser-flash photolysis technique. The temperature dependence of the relaxation constant of (Fe(6-Me-py)$\sb 2$(py)tren) (ClO$\sb 4)\sb 2$ doped in PSS polymer film from 300K-4.2K can be fit well to quantum-mechanical tunneling theory. It is concluded that the spin-state relaxation process of this complex occurs by a quantum-mechanical tunneling mechanism. The inverse relationship between the zero-energy separation and the apparent activation energy was observed in the complex series. This observation suggests that the spin-state interconversion process of these complexes is in the "normal" region, not the inverted region. (Abstract shortened with permission of author.) Made available in DSpace on 2014-12-15T23:19:03Z (GMT). No. of bitstreams: 1 8721791.pdf: 6925147 bytes, checksum: 147ebb8a251f8a60abe6f5474fd38099 (MD5) Previous issue date: 1987 Embargo set by: Seth Robbins for item 70548 Lift date: Forever Reason: Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs Restricted to the U of I community idenfinitely during batch ingest of legacy ETDs U of I Only 337 p. Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987. http://hdl.handle.net/2142/70382 (UMI)AAI8721791 Chemistry, Inorganic Dynamics and Mechanism of Spin-State Interconversion in Iron Spin-Crossover Complexes text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.