透過您的圖書館登入
IP:54.82.44.149
  • 學位論文

氰化橋鍵金屬簇化合物與單鏈磁鐵之結構與磁性探討

Structural and magnetic studies of CN bridged metal clusters and single chain magnets

指導教授 : 王瑜

摘要


利用水熱法,可以成功合成出兩種四核鐵四方格子,錯合物(1-1) [Fe4II(phen)8(CN)4](BF4)4]•2H2O、錯合物(1-2) [Fe4II(phen)4(CN)4Cl4]•3H2O。從結構來看,錯合物(1-1)具有四方格子形狀,四核鐵經由CN鍵將彼此相連。且在四方格子的中心具有Ci對稱。四方格子內具有兩種鐵,分別為Fe1與Fe2。由於分子內的CN disorder,所以空間中Fe1與Fe2具有兩種配位環境: [FeIIN4C2]以及[FeIIN6]。四方格子內四個Fe其中有兩個Fe屬於[FeIIN4C2]配位環境另外兩個Fe屬於[FeIIN6] 配位環境。從磁性實驗,屬於[FeIIN6] 配位環境的鐵在溫度高於300K時會從低自旋態轉換成高自旋態。錯合物(1-2) 也具有四方格子形狀,經由CN鍵將彼此相連,在四方格子的中心具有C2h對稱。其中Fe1為六配位環境由兩個CN鍵以及兩個雙牙基phen鍵結。 Fe2則是四配位環境由兩個NC鍵以及兩個氯離子鍵結。從磁性分析,錯合物(1-1)具有自旋交叉行為。錯合物(1-2)屬於順磁行為。 同樣的利用水熱法,可以合成出兩種四核四方格子分子鏈,錯合物(2-1) [Co4IICo2III(phen)6(CN)8Cl4][CoIICl4]•CH3OH、(2-2) [FeIINi2II(phen)2(CN)4Cl2]。錯合物(2-1)是一個分子鏈經由兩種Co4所組成的四方格子彼此相連成一維鏈。其中一個四方格子中心為Ci對稱另一個為C2對稱。分子鏈內由三種Co所組成:Co1六配位環境由四個CN鍵以及一個雙牙基phen鍵結; Co2為六配位環境由兩個NC鍵以及兩個雙牙基phen鍵結; Co3則是四配位環境由兩個NC鍵以及兩個氯離子鍵結。錯合物(2-2)與錯合物(2-1)具有相類似的結構,差別在於錯合物(2-2)是由Ni3Fe所組成的四方格子。將Co1取代成四配位四方平面的Ni1,Co2取代為Ni2,Co3取代為Fe。從磁性分析結果,錯合物(2-1)、(2-2) 屬於順磁行為,其中錯合物(2-1) Co具有較大的軌域貢獻。 一個新的由CN鍵做架橋的雙金屬分子鏈:[CrIII(CN)6MnIII(cyclam)]•6H2O; (cyclam = 1,4,8,11-Tetraazacyclotetradecane)。我們發現兩種晶體結構具有相同分子式多形體(3A),多形體(3B)。從磁性的分析,多形體(3A)屬於分子鏈磁鐵行為,而多形體(3B)不是。除此之外,經由吸水脫水的過程,(3A)具有磁海綿的性質。(3A)在有水的的情況下屬與分子鏈磁鐵,無水的狀態下呈現三度空間磁鐵。

關鍵字

單鏈磁鐵

並列摘要


Two types of tetra-nuclear molecular square complexes were synthesized by the hydrothermal method: one is [Fe4II(phen)8(CN)4](BF4)4]•2H2O (1-1) and the other is [Fe4II(phen)4(CN)4Cl4]•3H2O (1-2). The former one (1-1) has a square unit formed by four iron units, Fe4, linked by cyanide ligand with a Ci symmetry at the center of the square. There are two unique Fe ions in the structure: Fe(1) and Fe(2). Because of CN disorder in molecular square, Fe(1) and Fe(2) have two kinds of coordination environment: [FeIIN4C2] and [FeIIN6]. Fe of [FeIIN4C2] is always at the low spin (LS) state but Fe of [FeIIN6] can change the spin state from (LS) to high spin (HS) when temperature is higher than 300K. Complex (1-2) also has a square unit linked by cyanide ligand with a C2h symmetry at the center of the square; where Fe(1) is six-coordinated with two CN and two bi-dentate phen ligands; Fe(2) is four-coordinated with two NC groups and two chlorides. So Fe(2) is in HS state and Fe(1) is in LS state. From magnetic measurement, Compound (1-1) shows spin crossover behavior. Compound (1-2) shows paramagnetic behavior. Two types of tetra-nuclear molecular chain complexes were synthesized by the hydrothermal method: one is [Co4IICo2III(phen)6(CN)8Cl4][CoIICl4]•CH3OH (2-1) and the other is [FeIINi2II(phen)2(CN)4Cl2] (2-2). (2-1) is a molecular chain linked by two types of Co4 square unit: again one is Ci symmetry at the center of each square and the other is C2 symmetry at the center of each square; there are three unique Co ions in the chain: Co1 is six-coordinated with four CN and one bi-dentate phen ligand; Co2 is six-coordinated with two NC and two bi-dentate phen ligands; Co3 is tetra-coordinated with two NC and two chlorides. The structure of (2-2) is very similar to that of (2-1) except the the square unit is now Ni3Fe where Co1 is replaced by a 4-coordinated planar Ni1, Co2 is replaced by Ni2 and Co3 by Fe. From magnetic measurement, compound (2-1) and (2-2) shows paramagnetic behavior and Co ion in compound (2-1) have strong orbital contribution. A new one dimensional (1D) cyano-bridged bimetallic chain is reported here.: [CrIII(CN)6MnIII(cyclam)]•6H2O (cyclam = 1,4,8,11-Tetraazacyclotetradecane) is characterized recently by single crystal x-ray diffraction. We find two crystal structures with the same formula namely polymorph (3 A) and polymorph (3 B). From magnetic measurement, 3 A appears to be single chain magnet (SCM) but 3B is not. In addition, 3 A behaves like a magnetic sponge through hydration/dehydration process. The magnetic property of 3 A indicates that it is a SCM in hydrated form but becomes a 3D bulk magnet in dehydrated form.

並列關鍵字

single chain magnet

參考文獻


75. (a)Physical Method for Chemistry Russell S. Drago
36. T. Kajiwara, M. Nakano, Y. Kaneko, S. Takaishi, T. Ito, M. Yamashita, A. Igashira-
95. V. K. Pecharsky,; L. L. Miller,; K. A. Gschneidner, , Jr.; D. C. Johnston,
6. O. Hatlevik, W. E. Buschmann, J. Zhang, J. L. Manson, J. S. Miller, Adv. Mater. 1999, 11, 914
2. R.M. White, Science 1985, 229, 11–15.

延伸閱讀