王 瑜臺灣大學:化學研究所魏景怡Wei, Ching-YiChing-YiWei2010-06-302018-07-102010-06-302018-07-102008U0001-2107200818380300http://ntur.lib.ntu.edu.tw//handle/246246/187484本研究為鐵三價自旋交叉 (spin crossover) 錯合物{[Fe(3-OMe-salMen)2]2 [Ni(mnt)2] • xCH3CN}(x=0, 2)合成、結構鑑定與磁性研究之相關探討。{[Fe(3-OMe-salMen)2]2 [Ni(mnt)2] • xCH3CN}有三種不同型態 (polymorph)：A含兩個結晶溶劑分子 (x = 2)，而B和C不含任何結晶溶劑 (x = 0)。其中A的空間群屬於triclinic Pī，晶格參數為a = 9.402(2)， b = 10.476(2)， c = 16.636(3) Å，α = 87.17(3)，β = 77.38(3)，γ = 75.21(3) º；B的空間群屬於triclinic Pī， 晶格參數為a = 10.519(2)，b = 10.797(2)，c = 13.698(3) Å，α = 100.16(3)，β = 100.48(3)，γ = 99.80(3) º；C的空間群屬於monoclinic P21/n，晶格參數為a = 9.5747(19)，b = 24.916(5)，c = 12.404(3) Å，α = 90，β = 102.52(3)，γ = 90 º。正一價錯合陽離子{[Fe(3-OMe-salMen)2]+}是由兩個三牙基 (3-OMe-salMen) 的兩個氮原子和一個氧原子與中心三價鐵離子以八面體 (N4O2) 形式配位成；而負二價錯合陰離子 {[Ni(mnt)2]2-} 是兩個雙牙基 (mnt；C2N2S2) 的兩個硫原子與中心鎳離子以平面四方配位而成。 A在溫度5至350 K範圍為低自旋狀態 (low spin, S = 1/2)，而B與C呈現緩漸 (gradual) 的自旋轉換現象，自旋轉換溫度 (T1/2) 分別為290 K與120 K。依據熱重分析、磁性測量的結果發現，在溫度超過360 K時，A中結晶溶劑 (CH3CN) 可被移除，轉變為B為高自旋狀態 (high spin, S = 5/2)，且A、B間的結晶溶劑吸脫附特性與磁性性質轉變為可逆反應，並且可進一步從X光粉末繞射結果證明。此外，當A在移除結晶溶劑時施以外加壓力，A會轉變為C，且其間的轉變過程不具可逆性。 A、B與C晶體結構的陽離子層與陰離子層交錯排列情形非常相似。A與B的相鄰陽離子間藉由配位基的苯環間π-π作用力形成二聚物 (dimer)，而C的陽離子則因相鄰配位基間的近作用力 (short contact) 而形成一維鏈狀結構。由A與B的晶體堆疊相似性可以進一步確認兩者間的可逆反應是容易進行的，而C的晶體堆疊與A的差異性大，推測其間轉變的不可逆特性亦與此有關，且不同的晶體排列亦伴隨著不同之磁性性質。A cationic Fe(III) complex, [Fe(3-OMe-salMen)2]+, forms crystals with Ni(II) complex anion [Ni(mnt)2]2- in three forms in formula of [Fe(3-OMe-salMen)2]2 [Ni(mnt)2] • xCH3CN, (3-OMe-salMen = 2-({[2-(methyl-amino)ethyl]imino} methyl)-3-methoxyphenol; mnt = maleonitriledithiolate) where x =2 is designated as form A; x = 0 for other two forms (B and C). All three crystal structures are characterized by single crystal diffraction method. A belongs to triclinic space group, Pī, with cell parameters a = 9.402(2), b = 10.476(2), c = 16.636(3) Å, α = 87.17(3), β = 77.38(3) and γ = 75.21(3) º B also belongs to triclinic space group, Pī, with cell parameters a = 10.519(2), b = 10.797(2), c = 13.698(3) Å, α = 100.16(3), β = 100.48(3) and γ = 99.80(3) º C belongs to monoclinic space group, P21/n, with cell parameters a = 9.5747(19), b = 24.916(5), c = 12.404(3) Å, α = 90, β = 102.52(3) and γ = 90 º. The cation is an octahedrally coordinated (N4O2) iron(III) complex; the anion is a square planar nickel(II) complex. Iron(III) is coordinated by two tridentate ligands, 3-OMe-salMen. According to magnetic measurement, the iron(III) (d5) in A is at the low spin state (LS, S = 1/2) in the temperature range of 5~350 K, while B and C display a gradual spin transition between high spin (HS, S = 5/2) (6A1g) and low spin state (LS, 2T2g) with T1/2 ~ 290 K and 120 K, respectively. Based on the TGA, SQUID and in-situ powder XRD results, the solvent molecule CH3CN in A can be removed by heating at temperature higher than 360 K; meanwhile the spin state of iron(III) changes from LS to HS. B can be obtained from A by removing all the solvent molecules, CH3CN, from the lattice; however the process is completely reversible and accompanied with the structure change as evidenced by the in-situ X-ray powder diffraction. Furthermore, C can be obtained from A during the solvate extraction process with an external pressure. In contrary to the reversible transformation between A and B, the transformation from A to C is irreversible, and the phase transition from B to C is not found. The crystal packing of complex A, B and C are analogously arranged by alternate layers of complex cations and anions. The cations in complex A and B form dimer like pairs via π-π interaction of the phenyl rings of the ligands. As for C, such dimer like pairs no longer exist, the packing is quite different from those of A and B. It is plausible that the different molecular packing may cause the significant shift in magnetic transition temperature.謝誌 I文摘要 IIBSTRACT IVIST OF FIGURES VIIIIST OF TABLES XIIHAPTER 1 INTRODUCTION 1.1 Introduction of Spin Crossover 1.1.1 A Brief History 1.1.2 Crystal Field Theory 3.1.3 Spin Crossover Phenomenon 4.2 Iron (III) Spin Crossover Compounds 7.2.1 Tris(N,N-Disubstituted-Dithiocarbamato) Iron(III) Compounds 7.2.2 Iron(III) Spin Crossover Systems of Tridentate N2O Donating Schiff Base Ligands. 8.3 Research Motivation 13HAPTER 2 EXPERIMENTAL 17.1 Chemicals 17.2 Synthesis 18.2.1 Synthesis of (Bu4N)2 Ni(mnt)2 18.2.2 Synthesis of [Fe(3-OMe-salMen)2]Cl 18.2.3 Synthesis of [Fe(3-OMe-salMen)2]2[Ni(mnt)2]•2CH3CN (A) 19.2.4 Synthesis of [Fe(3-OMe-salMen)2]2[Ni(mnt)2] (B) 19.2.5 Synthesis of [Fe(3-OMe-salMen)2]2[Ni(mnt)2] (C) 20.3 Physical Measurements 21.3.1 Magnetic property measurement 21.3.2 Thermogravimetric analysis 22.3.3 X-ray absorption spectrum 22.3.4 Powder X-ray diffraction 24.3.5 X-ray Single Crystal Crystallography 25HAPTER 3 RESULTS AND DISCUSSION 27.1 Magnetic Properties 27.1.1 The reversibility between polymorph A and B 27.1.2 The unexpected two-step magnetic behavior 32.1.3 The magnetic properties and powder patterns of polymorph A, B and C 36.1.4 Pressure Effect 39.2 Electronic Configuration of Fe(III) 43.2.1 Fe K-edge absorption spectra 43.2.2 Fe LII III-edge absorption spectra 44.3 Molecular and Crystal Structures 49.3.1 The structure of [Fe (3-OMe-salMen)2]2[Ni(mnt)2]•2CH3CN (A) 49.3.2 The structure of [Fe (3-OMe-salMen)2]2[Ni(mnt)2] (B) 54.3.3 The structure of [Fe(3-OMe-salMen)2]2[Ni(mnt)2] (C) 59.3.4 Comprehensive Comparison 62HAPTER 4 CONCLUSIONS 70PPENDIX 73EFERENCE 893201180 bytesapplication/pdfen-US鐵三價自旋交叉磁性Iron (III)spin crossovermagnetic propertythesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/187484/1/ntu-97-R95223086-1.pdf