首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The white homoleptic high-spin iron(II) complexes Fe[TpMe2,4Cl]2 (1) was isolated in quantitative yield from reaction mixtures containing 1 equiv of FeCl2(THF)1.5 and 2 equiv of K[TpMe2,4Cl] (TpMe2,4Cl = hydrotris[(4-chloro-3,5-dimethyl-pyrazolyl)]borate). Its purple low-spin iron(III) counterparts 1[O3SCF3] and 1[PF6] were synthesized and isolated in 85% yields upon treatment of 1 with 1 equiv of silver triflate and silver hexafluorophosphate, respectively. The three paramagnetic compounds are air and thermally stable as solids and in solution; they were characterized by elemental analyses, IR, magnetic susceptibility measurements, 1H NMR, and Mössbauer spectroscopy. In addition, 1[PF6] was authenticated by a single-crystal X-ray diffraction. The two scorpionate ligands are κ3-N,N′,N′′ ligated to the central FeIII ion, forming an almost perfect FeN6 octahedron with an average Fe-N bond distance of 1.9551(18) Å. In addition, complex 1 which oxidizes reversibly at E1/2 = 0.483 V/SCE (ΔEp = 94 mV), remains high-spin (S = 2) when the temperature is lowered to 2 K.  相似文献   

2.
Two synthetic procedures have been employed that allow access to the new tetranuclear cluster [Fe4O2(O2CMe)6(N3)2(phen)2] (1), where phen is 1,10-phenanthroline. Complex 1 · 3MeCN displays an unusual structural asymmetry (observed for the second time) in its [Fe4O2]8+ core that can be considered as a hybrid of the bent (butterfly) and planar dispositions of four metal ions seen previously in such compounds with transition metals. Complex 1 has been characterized by variable-temperature magnetic susceptibility studies, and by IR and variable-temperature 57Fe Mössbauer spectroscopies. Magnetochemical data reveal a diamagnetic ground state (S=0) with antiferromagnetic body-body and body-wingtip interactions between the iron(III) ions of the butterfly core (Jbb=−11 cm−1, Jwb=−70 cm−1). Magnetochemical and Mössbauer studies on 1 show that its structural asymmetry has practically no influence on these properties compared with the more symmetric types.  相似文献   

3.
A one-dimensional polymeric-chain iron(II)-nickel(II) cyanido-bridged complex of the composition {[Fe(abpt)2(μ-Ni(CN)4)]·0.5H2O}n (1·0.5H2O), where abpt = 4-amino-3,5-di-2-pyridyl-4H-1,2,4-triazole, was prepared and characterized by elemental and thermal analyses, FTIR and 57Fe Mössbauer spectroscopies, and magnetic measurements. The incomplete spin crossover phenomenon was observed with approximately 12% of the frozen high-spin fraction at low temperatures and with the spin transition critical temperature above room temperature.  相似文献   

4.
A new complex [Ni(L)Fe(CN)5NO] · 2H2O (L = 4,6,6-trimethyl-1,9-diamino-3,7-di-aza-nona-3-ene) has been obtained and characterized by means of X-ray crystallographic analysis and magnetochemistry. The Fe(CN)5NO2− anion links to the Ni(L)2+ cation through two bridging cyanide groups in a bent fashion. The intrachain Ni?Ni and interchain Ni?Ni distances are equal to 9.81(8) and 7.75(1) Å, respectively. The magnetic behaviour of the complex indicates the zero field splitting parameter D higher than 3 cm−1 and the average exchange parameter (intra- and interchain) corresponding to direct Ni-Ni magnetic interaction in the crystal lattice equals ∼−0.2 cm−1.  相似文献   

5.
6.
The self assembly of [FeIII(L)]Cl2ClO4 (L = pentadentate macrocyclic ligand) with octacyano metallates [MIV(CN)8]4− (M = Mo, W) leads to bimetallic cyano-bridged 2-D coordination polymers of formula [{Fe(L)}3{M(CN)8}2]Cl·xH2O with M = Mo (2), or W (3). The structure of the tungsten analogue has been established by single crystal X-ray diffraction. The magnetic properties for both Mo and W derivative are reported.  相似文献   

7.
Two novel molecular magnetic materials, [RBzTPP][Ni(mnt)2] (mnt2− = maleonitriledithiolate, [RBzTPP]+ = 4-R-benzyltriphenylphosphinium; R = CN (1), Cl (2)) were synthesized and characterized by X-ray diffraction, IR spectroscopy, and magnetic susceptibility measurements. In crystal of 1, the [Ni(mnt)2] anions form a dimer via Ni?S and π?π stacking interactions between Ni(mnt)2 planes, and the C-H?Ni and C-H?N H-bonding interactions are found between the [Ni(mnt)2] anions and the neighboring [CNBzTPP]+ cations. The anions and cations of 2 stack into well-segregated columns in the solid state; and the Ni(III) ions form a 1D alternating chain in a Ni(mnt)2 column through intermolecular Ni?S, or π?π interactions with the Ni?Ni distances of 3.900, 4.198, and 4.165 Å. Magnetic susceptibility measurements for these complexes in the temperature range 1.8-300 K show that the overall magnetic behavior for 1 and 2 indicates the presence of antiferromagnetic interaction, but 1 exhibits an activated magnetic behavior in the high-temperature (HT) region together with a Curie tail in the low-temperature (LT) region.  相似文献   

8.
Li Liu  Lin Xu  Xizheng Liu  Bo Bi 《Inorganica chimica acta》2009,362(10):3881-12476
A novel fluorinated iron phosphite Fe2(HPO3)F2 (1) has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the orthorhombic space group Pnma (No. 51) with a = 7.3458(15) Å, b = 10.038(2) Å, c = 5.4947(11) Å, V = 405.16(14) Å3, Z = 4. Its structure is built up from iron(II) oxygen-fluorine FeO3F3 octahedra and HPO3 pseudo-tetrahedra, giving rise to a 3D inorganic framework. The infinite -Fe-O-Fe-F-Fe- linkage and -Fe-F-Fe- layer in the framework are the noteworthy structural features. Mössbauer spectrum shows the presence of Fe2+ in the octahedral coordination. Magnetic measurements indicate the existence of antiferromagnetic interactions.  相似文献   

9.
A novel linear bis(chlorido)-bridged Cu(II) compound with the ligand 7-azaindole (abbreviated as Haza) have been synthesized and fully characterized by spectroscopy, EPR and X-ray structure analysis. The geometry around the Cu(II) ion in the compound [Cu-μ-Cl2(Haza)2]n, is distorted octahedral with the basal plane formed by two chloride anions with a Cu-Cl distance of 2.286(1) Å and two nitrogen atoms of two trans-chelating Haza ligands with a Cu-N distance of 2.042(4) Å. The apical positions is formed by two chloride anions of a neighbouring unit at a distance of 3.143(2) Å. The Cu-Cl-Cu angle is 90.09(5)°, while the Cu-Cu distance is 3.8890(8) Å.The EPR powder spectrum appears as rhombic, displaying some extra features which were assigned to the differences in orientation of chains in the lattice, as their intensity appears to decrease on powdering. The magnetic susceptibility measurements, recorded from 5 to 300 K, agree with a very weak antiferromagnetic interaction in a chain with J = −2.6 cm−1.  相似文献   

10.
1,1′-Diethyl-2,2′,3,3′,4,4′,5,5′-octamethylferrocene has been utilized as a one-electron donor in the synthesis of a tetracyanoethylene charge-transfer salt, [Fe(C5EtMe4)2]+[TCNE]. Structural characterization shows that it adopts an arrangement of anions and cations completely different from the usual π stacking seen in analogous decamethylferrocenium compounds. The TCNE radical sits along side of the ferrocene, nearly perpendicular to the planes of the C5 rings. The nearly square geometry of the TCNE anion creates disorder over two orientations. [Fe(C5EtMe4)2]+[TCNE] is a simple paramagnet exhibiting neither long-range magnetic order nor slow paramagnetic relaxation to the lowest measured temperatures (ca. 1.8 K) as determined by both ac and dc magnetic susceptibility and Mössbauer spectroscopy (ca. 1.3 K).  相似文献   

11.
The synthesis, X-ray structure, spectroscopic and magnetic properties of a zig-zag formato-bridged chain complex with the formula [Cu(dpyam)(μ-O2CH)(OH2)]n(NO3)n (1) (in which dpyam = di-2-pyridylamine) is described.The geometry of the copper(II) ion is distorted square pyramidal with a basal plane consisting of two nitrogen atoms of the dpyam ligand (Cu-N distances 1.987(3) and 2.010(3) Å) and two oxygen atoms of two different formato ligands (Cu-O distances 1.974(2) and 1.975(2) Å). A coordinated water molecule occupies the axial position at a distance of 2.222(3) Å. The copper atoms are bridged unsymmetrically by a formato anion in a syn-anti arrangement, resulting in a polymeric zig-zag chain structure.The magnetic susceptibility measurements (5-280 K) agree with a very weak ferromagnetic chain interaction between the Cu centres with a J value of 0.75 cm−1.  相似文献   

12.
Two novel dinuclear nickel(II) complexes [Ni2(ntb)2(μ-tp)(H2O)1.61(CH3OH)0.39](NO3)2·5.13CH3OH·2.25H2O (1) and [Ni2(ntb)2(μ-fum)(H2O)(CH3OH)](NO3)2·6CH3OH·H2O (2) (tp = terephthalate dianion, fum = fumarate dianion, ntb = tris(2-benzimidazolylmethyl)amine) containing tetradentate poly-benzimidazole ligand were synthesized and structurally characterized by IR spectra, UV-Vis, elemental analysis and X-ray crystallography. The Ni(II) ions in 1 and 2 have distorted octahedral geometry with four nitrogen atoms of ntb, one oxygen atom of water and one oxygen atom supplied by the carboxylate group of the bridged dicarboxylato ligand. Complexes 1 and 2 consist of terephthalato- and fumarato-bridged dinickel(II) centers in bis(monodentate) bonding fashion. The Ni?Ni distances are 11.333 Å for 1 and 8.966 Å for 2. The magnetic susceptibility measurements at variable temperature show that two complexes exhibit weak antiferromagnetic interactions between nickel(II) ions with J values of −0.25 cm−1 and −0.36 cm−1, respectively.  相似文献   

13.
Reaction in air of iron(III) salts with tripodal ligands formed from the condensation of tris-(2-aminoethyl)amine (tren) with three equivalents of 2-pyridinecarboxaldehyde (py) or 1-methyl-2-imidazolecarboxaldehyde (NCH3Im) yielded exclusively the iron(II) complexes, [Fetren(py)3]X2 (X=ClO4 − or PF6 −) or [Fetren(NCH3Im)3](ClO4)2. The complexes were characterized by EA, IR, UV, Mössbauer, and mass spectroscopy. The structure of [Fetren(py)3](ClO4)2 was determined at 100 and 290 K. The structures are essentially the same and feature an octahedral iron with facial coordination of pyridine and imine nitrogen atoms with average bond distances of 1.9747 and 1.9523 Å, respectively, at 290 K. The short Fe-N bond distances and lack of variation with temperature support a low spin, 1A, assignment for the iron atom. The center nitrogen atom of the tren is essentially planar and is outside of bonding interaction with the iron, 3.45 Å. The low spin assignment is supported by Mössbauer spectroscopy, which reveals the presence of two low spin forms that are not in thermal equilibrium. In contrast, the Mössbauer spectrum of [Fetren(NCH3Im)3](ClO4)2 reveals the presence of both high spin, 5T, and low spin, 1A, forms at room temperature, which on cooling to 77 K simplify to the low spin form.  相似文献   

14.
The first linear bis(chlorido)-bridged Cu(II) compound with the ligand 2-amino-5-nitropyrimidine (abbreviated as anpyr), [Cu(μ-Cl)2(anpyr)2]n, has been synthesized and fully characterized by spectroscopy, EPR and X-ray structure analysis. The basal plane around the Cu(II) ion is formed by two chloride anions with a Cu-Cl distance of 2.2513(6) Å and two nitrogen atoms of two trans-located anpyr ligands with a Cu-N distance of 2.068(2) Å. The apical positions of the distorted octahedral geometry are formed by two Cl anions of a neighbouring unit with a distance of 2.8690(8) Å. The Cu-Cl-Cu angle is 94.75(3)°, while the Cu-Cu distance is 3.791 Å. The Cu-bis-μ-chlorido-Cu array provides in this way a 2D linear chain.A neighbouring pair of symmetry-related polynuclear chains is linked through hydrogen bonds with a N···N distance 3.027(3) Å, forming into a kind of Watson-Crick-like pair of hydrogen bonds. Another H-bond is formed by the amine nitrogen to one of the chloride anions with a N···Cl distance 3.248(2) Å.The EPR powder spectrum appears as rhombic with g1 2.20, g2 2.12; g3 2.05, with unresolved hyperfine splittings. Analysis of the magnetic susceptibility measurements, recorded from 2 to 300 K, indicates a very weak antiferromagnetic interaction between the metal ions (J = −2 cm−1).  相似文献   

15.
A new rare variety asymmetric μ2-1,1-azido bridged copper(II) complex has been synthesized and characterized structurally and magnetically. The complex [Cu2L22-1,1-N3)2] · H2O · CH3OH (L = 1-(N-ortho-hydroxyacetophenimine)-2-aminoethane) (1), crystallizes in monoclinic space group, P21/n, with a = 9.469(4) Å, b = 12.526(8) Å, c = 12.899(10) Å, β = 105.79(6)°, V = 1472.2(16) Å3. X-ray study reveals that he Cu-N(azide)-Cu angles in this complex is 90.4°. This is unusually low in comparison to that of the same angle in other end-on azido-bridged binuclear complexes. Though a strong ferromagnetic interaction between the metal centers is expected in the complex, the coupling has actually been found to be antiferromagnetic (J = −4.2 cm−1), instead. To rationalize this paradoxical magnetic behavior, DFT calculation of this and other four complexes with very similar structure have been performed within broken symmetry framework. The calculated magnetic coupling constants (J) are in excellent agreement, both in sign and in the magnitude of the exchange interaction, with the experimental data, and the spin density map is correctly reproduced.  相似文献   

16.
The reaction of [FeII(H2O)6](BF4)2 with tris(2-pyridylmethyl)amine (TPyA) and triethylamine in methanol under aerobic conditions forms [(TPyA)FFeIIIOFeIIIF(TPyA)](BF4)2 · 0.5MeOH (1), in which each Fe(III) ion is coordinated to a TPyA and an F ion as well as an oxo ion (O2−) linking two Fe(III) ions. 1 has offset face-to-face π-π interactions between the dimers, and possesses a supramolecular network structure. The magnetic susceptibility of 1 can be fit with g = 2.0, J/kB = − 153 K (106 cm−1), and θ = − 0.3 K [H = − 2JSa · Sb]. These indicate that very strong antiferromagnetic interactions occur via the oxo bridge within the Fe(III) dimer and weak antiferromagnetic interactions between the dimers.  相似文献   

17.
The reaction of M(NO3)2·xH2O (M = Cu, Ni and Co; x = 3 for Cu and x = 6 for Co/Ni), imidazole (Im) and sodium dicyanamide (dca) afforded the complexes [M(Im)2(dca)2] (where M = Cu for 1, M = Ni for 2, and M = Co for 3). All of them have been characterized structurally by single crystal X-ray diffraction measurements. X-ray analysis reveals that the dicyanamido ligand features the μ1,3 bridging mode that led to the formation of two-dimensional structure of complex 1 while complexes 2 and 3 attribute an infinite one-dimensional chain like structure to generate the fascinating molecular assemblies. The {N(CN)2} ligands present in the complexes 2 and 3 are coordinated in end-to-end (μ1,5) fashion. All the complexes have distorted octahedral geometry around the central metal ion and coordinated by two amine nitrogen atoms from imidazole ligands and four nitrogen atoms from dca ligands. The variable temperature (2-300 K) magnetic susceptibility measurements showed that the magnetic interaction between the metal centers in the complex 1 is dominantly ferromagnetic while the metal ions in complex 3 are antiferromagnetically coupled. On the contrary, complex 2 is a simple paramagnet. The results of magnetic model are in good agreement with the experimental data.  相似文献   

18.
A 2D layer complex 1 and a linear trinuclear complex 2 with mixed ligands have been synthesized and characterized by elemental analyses, IR and single-crystal X-ray diffraction. In 1, the Mn(II) ions are six-coordinated and lie in distorted octahedron coordination environments. Complex 1 is connected into a 2D layer structure based on a linear trinuclear Mn3(admtrz)4(N3)6 (admtrz = 4-amino-3,5-dimethyl-1,2,4-triazole) building unit with either (6,3) topology when Mn1 cations as three-connected nodes or (4,4) network when the coordination trinuclear units being regarded as four connected nodes. In 2, the Co(II) ions are in slightly distorted octahedron coordination geometries. The magnetic behaviors are investigated in the temperature range 1.8-300 K. The magnetic susceptibility measurements show that the Mn(II) ions of complex 1 are weakly antiferromagnetically coupled with g = 1.98(1), J1 = −6.31(5) cm−1 and J2 = −1.88(1) cm−1. There is dominant zero field splitting (ZFS) effects with g values, g// = 2.38(2) and g = 4.96(4), indicated a significant presence of the spin-orbit coupling and magnetization experiment reveals large, uniaxial zero-field splitting parameters of D = −29.55 cm−1 for 2.  相似文献   

19.
A novel binuclear copper(II) complex [Cu2L(μ-SO4)](PF6)2 (1) (L = 3,5-bis (bis(pyridine-2-ylmethyl)amino)methyl)-4H-1,2,4-triazol-4-amine) has been synthesized and structurally characterized. X-ray structure shows that the two copper(II) atoms are bridged by one bidentate sulfate ion and the 1,2,4-triazole ring of L with Cu1?Cu2 distance of 4.404 Å. Each copper(II) center has a distorted trigonal-bipyramidal configuration. Variable-temperature magnetic susceptibility studies (2-300 K) indicate the existence of weak antiferromagnetic coupling between the copper(II) ions in complex 1. The interaction of complex 1 with calf thymus DNA (CT-DNA) has been studied by UV absorption, fluorescence spectroscopy, circular dichroism spectroscopy, viscosity and cyclic voltammetry. Furthermore, complex 1 was able to promote single and double strand DNA cleavage in both aerobic and anaerobic conditions, the pseudo-Michaelis-Menten kinetic parameters kcat = 2.58 h−1 and Km = 1.2 × 10−4 M were obtained for 1. The hydrolytic cleavage of DNA by the complex was supported by the evidence from free radical quenching, anaerobic experiment, thiobarbituric acid-reactive substances (TBARS) assay.  相似文献   

20.
A 2D grid-like copper(II) complex [Cu(N3)2(pyz)](pyz = pyrazine) (1) has been synthesized and characterized by single crystal X-ray analysis and magnetic measurements. The 2D grid-like network of 1 consists of 1D chain of Cu-pyz units connected by end-on azido bridge. 1 crystallizes in the monoclinic space group C2 with a = 15.148(6) Å, b = 6.877(2) Å, c = 3.4591(12) Å and Z = 2. The magnetic investigation showed the presence of an antiferromagnetic interaction between the copper(II) ions mainly mediated through pyrazine bridge.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号