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。
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.
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