Zum Spingleichgewicht5T2−1A1 in Fe(II)py 2 phen(NCS) 2

Zusammenfassung Die magnetischen, spektralen und strukturellen Eigenschaften des gemischten Amminkomplexes [Fe(II)py ₂ phen(NCS)₂] werden diskutiert. Der Orbitalparamter liegt mit 11 700 cm^–1 nahe der Spinpaarungsenergie für den mittleren kovalenten Fall 11 000 bis 12 000 cm^–1 und erlaubt so ein Spingleichgewicht zwischen den Spektralzuständen⁵T₂–¹A₁. Dieses Gleichgewicht wird durch magnetische Messungen bei verschiedenen Temperaturen nachgewiesen.

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On the spin equilibrium⁵T₂–¹A₁ in [Fe(II)py₂phen(NCS)₂]

The magnetic, spectral and structural properties of the mixed ammine [Fe(II)py ₂ phen(NCS)₂] are discussed. The orbital parameter of about 11 700 cm^–1 near to the spin-pairing energy for the mean covalent case 11 000 to 12 000 cm^–1 allows a spin equilibrium between the spectral states⁵T₂–¹A₁, put in evidence by the magnetic measurements at different temperatures.

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Mit 3 Abbildungen

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Herrn Prof. Dr.H. Nowotny gewidmet.     

自旋交叉配合物[Fe(mtt)(phen)(NCS)2]·py的合成和磁性研究

设计制备了一个新的自旋交叉配合物[Fe(mtt)(phen)(NCS)2·]py。通过元素分析、红外光谱、质谱和紫外光谱等方法对该配合物进行结构表征。变温磁化率研究发现该配合物的自旋转换温度为Tc↑=197K,Tc↓=188K,回滞宽度9K。通过与同体系其他配合物的比较发现,配体的修饰对自旋交叉临界温度以及回滞宽度都有显著影响。     

对自旋交叉化合物[Fe(dpq)(py)2(NCS)2]·H2O·py和[Fe(dpq)(py)2(NCSe)2]·1.5H2O的研究

为了研究配体修饰对自旋交叉现象的影响,我们合成了两个Fe(Ⅱ)自旋交叉的配合物[Fe(dpq)(py)₂(NCS)₂]·H₂O·py和[Fe(dpq)(py)₂(NCSe)₂]·1.5H₂O,(dpq=二吡嗪[2,3-f:2′3′-h]喹喔啉,py=吡啶)。通过对这两个配合物磁性质和穆斯堡尔谱的研究,发现和用邻啡咯啉配体合成的配合物比较,配体的修饰对自旋交叉性质以及其临界温度     

对自旋交叉化合物[Fe(dpq)(py)2(NCS)2]·H2O·py 和[Fe(dpq)(py)2(NCSe)2]·1.5H2O的研究

为了研究配体修饰对自旋交叉现象的影响,我们合成了两个Fe?自旋交叉的配合物犤Fe(dpq)(py)2(NCS)2犦·H2O·py和犤Fe(dpq)(py)2(NCSe)2犦·1.5H2O,(dpq=二吡嗪犤2,3-f:2'3'-h犦喹喔啉,py=吡啶)。通过对这两个配合物磁性质和穆斯堡尔谱的研究,发现和用邻啡咯啉配体合成的配合物比较,配体的修饰对自旋交叉性质以及其临界温度都有着显著影响。     

自旋交叉配合物[Fe(ttd)2(NCS)2]·H2O的合成和磁性研究

The ligand ttd(ttd=1,4,8,9-Tetraaza-triphenylene-2,3-dicarbonitrile) and a novel spin crossover complex [Fe(ttd)₂(NCS)₂]·H₂O were synthesized, and characterized by elemental analysis, IR, MS, and UV-vis spec-troscopy. The temperature dependence of magnetic susceptibility shows that there are a little break between 150～190K and an unusual step transition with a 50K width between 190～240K. Compared with the other complexes with the resemble structure, it can be found that the influence of ligand is very notable.     

常温自旋交叉配合物[Fe(dpp)(Mepy)2(NCS)2]的合成与磁性研究

设计制备了一个新的常温自旋交叉配合物[Fe(dpp)(Mepy)2(NCS)2]。通过元素分析、红外光谱、电喷雾质谱和紫外光谱等方法对该配合物进行结构表征。变温磁化率研究发现该配合物的自旋转换温度Tc为330K。通过与同体系其他配合物的比较发现,配体的修饰对自旋交叉临界温度以及回滞宽度都有显著影响。     

常温自旋交叉配合物[Fe(dpp)(Mepy)2(NCS)2]的合成与磁性

设计制备了一种新的常温自旋交叉配合物[Fe(dpp)(Mepy)2(NCS)2]. 通过元素分析、红外光谱、电喷雾质谱和紫外光谱等测试技术对该配合物进行了结构表征. 变温磁化率研究发现,该配合物的自旋转换温度Tc=330 K. 通过与同体系其它配合物的比较发现,配体的修饰对自旋交叉临界温度以及回滞宽度均有显著影响.     

Spin crossover transition of Fe(phen)2(NCS)2: periodic dispersion-corrected density-functional study

Periodic dispersion corrected DFT calculations have been performed to study the spin-crossover transition of Fe(phen)(2)(NCS)(2) in the molecular and in the crystalline state. We show that London dispersion interactions play a crucial role in the cohesion of the crystals. Based on calculations of vibrational eigenstates of the isolated molecule and of the crystalline phase in both the low- and high-spin states, the transition entropies and enthalpies have been calculated. We demonstrate that, due to the stabilization of the low-spin state by intermolecular dispersion forces, the transition enthalpy at the transition temperature is larger for the crystalline phase in comparison with an isolated molecule. The effective coordination number of the nitrogen atoms of the ligands around the iron atom has been identified as the order parameter driving the quasi-reversible low-spin to high-spin transition in the crystal. Finally, using constrained geometry relaxations at fixed values of the coordination number, we computed the energy barrier of the LS to HS transition and found it to be in a reasonable agreement with the experimental value.     

自旋交叉配合物[Fe(dpq)2(NCS)2]·1.5H2O的合成和磁性研究

自旋交叉配合物的研究是分子磁化学中的一个重要领域,并已引起人们的普遍关注。近期我们合成了一个新的配体dpq(dpq=dipyrazine[2,3f:2,3h]quinoxaline )和新的自旋交叉配合物[Fe(dpq)₂(NCS)₂]·1.5H₂O。通过元素分析、红外光谱、质谱、核磁共振、紫外光谱等方法对其结构进行了表征。变温磁化率和穆斯堡尔谱学的研究表明标题化合物是一个新颖的自旋交叉配合物,而且显示出不常见的15K回滞宽度,在降温时伴有一小台阶。通过对比发现,配体的共轭性在自旋交叉配合物中的影响是非常重要的。     

Spin transition in [Fe(phen)2(NCS)2] and [Fe(bipy)2(NCS)2]: Hysteresis and effect of crystal quality

Detailed magnetic susceptibility measurements on the polycrystalline complexes [Fe(phen)₂(NCS)₂] (phen = 1.10-phenanthroline) and [Fe(bipy)₂(NCS)₂] (bipy = 2,2′-bipyridine) have revealed a narrow hysteresis in both systems indicative of a first-order nature of the spin transition ⁵T_2g(O_h) ? ¹ A_tg(O_h). The crystal quality, in particular crystal defects (through preparation or grinding), have been shown to influence strongly the spin transition behaviour.     

Crystallochemical causes of the different thermal properties of [Cu(py)2(NCS)2] and [Cu(4-Mepy)2(NCS)2] complexes

The crystal structures and thermal behaviour of [Cu(py)₂(NCS)₂] (at 293) and [Cu(4-Mepy)₂(NCS)₂] and 180 K) complexes have been compared with their different temperature behaviour. It was found that the thermal stability of coordinated thiocyanate ligands in the course of thermal decomposition depends not only on the properties of the ligand L, but it is related to the arrangement of the thiocyanatocopper chains in the crystal structures.     

Effect of metal dilution on the light-induced spin transition in [Fe(x)Zn(1-x)(phen)2(NCS)2] (phen = 1,10-phenanthroline)

The thermal and light-induced spin transitions in [Fe(x)Zn(1-x)(phen)2(NCS)2] (phen = 1,10-phenantholine) have been investigated by magnetic susceptibility, photomagnetism and diffuse reflectivity measurements. These complexes display a thermal spin transition and undergo the light-induced excited spin state trapping (LIESST) effect at low temperatures. For each compound, the thermal spin transition temperature, T1/2, and the relaxation temperature of the photo-induced high-spin state, T(LIESST), have been systematically determined. It appears that T1/2 decreases with the metal dilution while T(LIESST) remains unchanged. This behaviour is discussed on the basis of the kinetic study governing the photo-induced back conversion.     

MÖSSBAUER- und Infrarotspektren von Addukten des K4[Fe(CN)6] mit Antimontrihalogeniden

Mössbauer- and IR Spectra from the Addition Compounds of K₄[Fe(CN)₆] with Antimony Trihalides By the reaction of K₄[Fe(CN)₆] with SbX₃ in the melt (X = Cl, Br) or in SO₂ solution (X = F) the addition compounds K₄[Fe(CNSbX₃)₆] (X = F, Cl) and K₄[Fe(CNSbX₃)₄(CN)₂] (X = Cl, Br) are formed. The IR spectra of these compounds have been interpreted. The MÖSSBAUER spectra are single lines which exhibit a slight broadening compared with K₄[Fe(CN)₆] · 3 H₂O. The values of the isomer shifts following the order of the LEWIS acid strengths of the SbX₃ molecules correspond to a small but significant increase of the s-electron density, which is explained by the increasing influence of the π-acceptor function of the ligands.     

混合配体配合物[Cd2(phen)4(bmal)2]·3H2O的合成与晶体结构研究

A novel binucleus mixed-ligand[Cd₂(phen)₄(bmal)₂]·3H₂O (phen=phenanthroline; bmal=benzylmalonic acid radical) has been synthesized by the reaction of phen and bmal with cadmium(Ⅱ) salt. X-ray crystal structure analysis was carried out to determine the crystal structure of the title complex. The crystal of the title complex belongs to monoclinic system with space group P2₁/c, a=1.119 1(8) nm, b=2.480 5(17) nm, c=1.063 4(8) nm, β=142.042(12)°, Z=4, V=2.887(3) nm³, D_c=1.613 g·cm^-3, R₁=0.046 2, wR₂=0.115 6, F(000)=1 424. One carboxyl of bmal is coordinated to Cd(1) with monodentate form, the others are coordinated to Cd(2) with bidentate form. The complexes form a 1-D chain structure bridged by hydrogen bonds that formed by uncoordinated water and oxygen atom of carboxyl group in bmal, the 2-D network structure was formed by π-π interaction of neighbouring phen. CCDC: 257080.     

Reactivity of [Te6Fe8(CO)24]2− and Its Conversion to [Te4Fe5(CO)14]2−

Whereas reaction of [PhCH₂NMe₃]₂|Te₆Fe₈(CO)₂₄] (1) in refluxing CH₂CI₂ forms Fe₂(CO)₆(μ0-) TeCH₂Te), treatment of 1 with Ph₂SnCl ₂ or Mel gave the oxidation product Te₂Fe₃(CO)₉. Oxidation of 1 with [Cu(CH₃CN)₄]BF₄ afforded Te₂Fe₃(CO)₉ in good yield. Cluster 1 was converted to [PhCH₂NMe₃][Te₄Fe₅(CO)₁₄] (2) in MeOH/CH₂Cl₂ solution. Cluster 2 was structurally characterized by single-crystal X-ray diffraction and spectral methods. Complex 2 is composed of two Te₂Fe₂(CO)₆ fragments linked by one Fe(CO)₂ group. 2 crystallizes in the orthorhombic space group Pbcn with a = 13.351 (4) Å, b = 13.417 (4) Å, c = 26.077 (3) Å, V = 4671 (2) Å ₃, Z = 4.