The reduction of fullerene C60 by zinc dust in the presence of crystal violet cations (CV+) yielded a deep‐blue solution, from which crystals of (CV+)(C60.?) ? 0.5 C6H4Cl2 ( 1 ) were obtained by slow mixing with n‐hexane. The salt contained isolated, closely packed zigzagged chains that were composed of C60.? radical anions with a uniform interfullerene center‐to‐center distance of 9.98 Å. In spite of the close proximity of the fullerenes, they did not dimerize, owing to spatial separation by the phenyl substituents of CV+. The room‐temperature conductivity of compound 1 was 3×10?2 S cm?1 along the fullerene chains. The salt exhibited semiconducting behavior, with an activation energy of Ea=167 meV. Spins localized on C60.? were antiferromagnetically coupled within the fullerene chains, with a Weiss temperature of ?19 K without long‐range magnetic ordering down to 1.9 K. 相似文献
A new dinuclear iron(Ⅲ) complex has been synthesized and structurally characterized by X-ray crystallography: [FeⅢ2(L)(C6H5COO)(SO4)(CH3OH)2]·CH3CN·CH3OH(1, H3 L = N,N'-bis(salicylidene)-1,3-diamino-2-propanol). Complex 1 belongs to orthorhombic space group Pna21 with a = 11.4400(8), b = 22.9705(2), c = 12.5712(9) , V = 3303.5(4) 3, Z = 4, F(000) = 1576, Dc = 1.531 g·cm–3, Mr = 761.36, μ = 1.007 mm–1, S = 1.014, the final R = 0.0505 and wR = 0.1018. The crystal packing is stabilized by intermolecular O–H···O hydrogen bonds, forming an extended one-dimensional chain structure. The temperature dependence of magnetic susceptibility measurement shows that antiferromagnetic interaction is propagated between the metal centers. Fit as dinuclear arrangement gave parameters of J = 19.7 cm-1, g = 1.89 and R2 = 0.9999. 相似文献
Poly(trifluoromethyl)fullerene S6‐C60(CF3)12 was reduced by sodium fluorenone ketyl in the presence of (PPN)Cl (PPN=bis(triphenylphosphine)iminium) to afford the salt (PPN)[C60(CF3)12] ( 1 ), which contains C60(CF3)12.? radical anions. In the crystal structure of 1 , C60(CF3)12.? layers alternate with the PPN+ cations. There are short F ??? F contacts between C60(CF3)12.? radical anions within the layers but no C ??? C contacts. DFT calculations revealed that the negative charge on C60(CF3)12.? is distributed mainly between sp2 carbon and fluorine atoms, whereas spin density is localized mainly on the fullerene‐cage sp2 carbon atoms. IR and UV/Vis/NIR spectra in the solid state and solution showed characteristic changes relative to those of neutral S6‐C60(CF3)12 due to the formation of radical anions. The solid‐state electronic spectrum of 1 exhibits a single broad band at 738 nm attributed to C60(CF3)12.?. Crystals of 1 show a narrow EPR signal with g=2.0025 (ΔH=0.45 mT) at 300 K. The temperature dependence of the integral intensity follows the Curie–Weiss law with a negative Weiss temperature of ?11.8 K (30–300 K) indicating antiferromagnetic interaction of spins. This dependence was approximated by the Heisenberg model for one‐dimensional chains of antiferromagnetically interacting spins with exchange interaction J/kB=?9.1 K. It was assumed that magnetic interaction between the C60(CF3)12.? spins in the layers is mediated by short F ??? F contacts. 相似文献
The use of the mononuclear rhenium(IV) precursor [ReBr5(H2pydc)]? (H2pydc=3,5‐pyridinedicarboxylic acid) as a metalloligand towards dysprosium(III) afforded the first heterobimetallic ReIV–DyIII complex. Crystal structures and static and dynamic magnetic properties of both rhenium‐containing species are reported herein. The 5d–4f compound shows an extended 1D structure and the AC magnetic measurements reveal frequency dependence at low temperature suggesting slow relaxation of the magnetization. 相似文献
A series of compounds with Sc3N@Ih-C80 in the neutral, monomeric, and dimeric anion states have been prepared in the crystalline form and their molecular structures and optical and magnetic properties have been studied. The neutral Sc3N@Ih-C80 ⋅ 3 C6H4Cl2 ( 1 ) and (Sc3N@Ih-C80)3(TPC)2 ⋅ 5 C6H4Cl2 ( 2 , TPC=triptycene) compounds both crystallized in a high-symmetry trigonal structure. The reduction of Sc3N@Ih-C80 to the radical anion resulted in dimerization to form diamagnetic singly bonded (Sc3N@Ih-C80−)2 dimers. In contrast to {[2.2.2]cryptand(Na+)}2(Sc3N@Ih-C80−)2 ⋅ 2.5 C6H4Cl2 ( 3 ) with strongly disordered components, we synthesized new dimeric phases {[2.2.2]cryptand- (K+)}2(Sc3N@Ih-C80−)2 ⋅ 2 C6H4Cl2 ( 4 ) and {[2.2.2]cryptand- (Cs+)}2(Sc3N@Ih-C80−)2 ⋅ 2 C6H4Cl2 ( 5 ) in which only one major dimer orientation was found. The thermal stability of the (Sc3N@Ih-C80−)2 dimers was studied by EPR analysis of 3 to show their dissociation in the 400–460 K range producing monomeric Sc3N@Ih-C80.− radical anions. This species shows an EPR signal with a hyperfine splitting of 5.8 mT. The energy of the intercage C−C bond was estimated to be 234±7 kJ mol−1, the highest value among negatively charged fullerene dimers. The EPR spectra of crystalline (Bu3MeP+)3(Sc3N@Ih-C80.−)3 ⋅ C6H4Cl2 ( 6 ) are presented for the first time. The salt shows an asymmetric EPR signal, which could be fitted by three lines. Two lines were attributed to Sc3N@Ih-C80.−. Hyperfine splitting is manifested above 180 K due to the hyperfine interaction of the electron spin with the three scandium atoms (a total of 22 lines with an average splitting of 5.32 mT are observed at 220 K). Furthermore, each of the 22 lines is additionally split into six lines with an average separation of 0.82 mT. The large splitting indicates intrinsic charge and spin density transfer from the fullerene cage to the Sc3N cluster. Both the monomeric and dimeric Sc3N@Ih-C80− anions show an intrinsic shift of the IR bands attributed to the Sc3N cluster and new bands corresponding to these species appear in the NIR range of their UV/Vis/NIR spectra, which allows these anions to be distinguished from neutral species. 相似文献
Finally, a structure with well‐resolved C 60 3? ions and S=1/2 spin system : The two novel title compounds have clearly S=1/2 and not S=3/2 electronic states, as expected for the occupation of the triply degenerate LUMO of C60. These structures with well‐ordered fullerene trianions show that the expected Jahn–Teller distortion is not observable in X‐ray diffraction experiments.
Non‐stoichiometric wüstite particles (Fe1?yO) are synthesized using the controlled room‐temperature hydrolysis of the organometallic precursor {Fe[N(SiMe3)2]2}. Particles stabilized by hexadecylamine with a diameter of ~5 nm are obtained. For such small nanoparticles, a distorted crystallographic structure is evidenced by wide‐angle X‐ray scattering at room temperature and reported for the first time. The study of the magnetic properties indicates that these particles are composed of an antiferromagnetic core surrounded by a ferromagnetic shell. According to the Néel theory, we demonstrate that this shell consists of 1.5 % of Fe3+ ions ferromagnetically coupled with Fe2+ ions. 相似文献
A linear tetranuclear 3d–4f Co2Dy2 cluster assembled from a polydentate Schiff base exhibits single‐molecule magnet (SMM) behavior with an anisotropic barrier of 33.8 K. Due to the presence of diamagnetic cobalt(III) ions, the tetranuclear cluster of 1 behaves magnetically like a dinuclear Dy2 system. However, the diamagnetic segment might efficiently minimize undesirable intermolecular magnetic interactions, thereby improving the performance of the SMM behavior of 1 . This discrete complex presents us with a unique opportunity to study the magnetic properties and to probe the dynamics of magnetization in a magnetically isolated Dy2 system. 相似文献
A new salt, (PPN+)2(C702?) ? 2 C6H4Cl2 ( 1 ), which contains C702? dianions, has been obtained as single crystals (PPN+=bis(triphenylphosphine)iminium cation). The C702? dianions form polymeric zigzag (C702?)n chains, in which the fullerene units are bonded through single C? C bonds of length 1.581(5)–1.586(6) Å. The distance between the centers of neighboring C702? units is 10.441 Å. The optical and magnetic properties of (C702?)n have also been studied. Decreasing the symmetry of C70 in the polymer activate about 20 new IR bands in addition to the 10 IR‐active bands of the starting C70. The polymeric structure shows absorptions in the visible and NIR regions, with three main bands at 890, 1200, and 1550 nm, instead of one band of isolated C702? dianions at 1165–1184 nm. We concluded that the (C702?)n polymer was diamagnetic, with a negative molar magnetic susceptibility of ?3.82×10?4 emu mol?1 per C702? dianion. The polymer is EPR silent and a weak narrow EPR signal in salt 1 is due to impurities, which only constitute 0.84 % of spin S=1/2 of the total amount of fullerene C70. 相似文献
The cobalt ferrite nanoparticles were prepared by coprecipitation in the presence of poly (N-vinylpyrrolidone) (PVP) and characterized by XRD, TEM, EDX and magnetometry. XRD results suggest the formation of pure cobalt ferrite. The mean particle sizes of CoFe2O4 samples annealed at 400 ℃ and 600 ℃ were ca. 6 and 25 nm, respectively as obtained by transmission electron microscopy (TEM). The magnetic measurements indicated that nano-particles obtained at 400 ℃ were superparamagnetic while that prepared at 600 ℃ were ferrimagnetic. 相似文献
Layered elemental materials, such as black phosphorus, exhibit unique properties originating from their highly anisotropic layered structure. The results presented herein demonstrate an anomalous anisotropy for the electrical, magnetic, and electrochemical properties of black phosphorus. It is shown that heterogeneous electron transfer from black phosphorus to outer‐ and inner‐sphere molecular probes is highly anisotropic. The electron‐transfer rates differ at the basal and edge planes. These unusual properties were interpreted by means of calculations, manifesting the metallic character of the edge planes as compared to the semiconducting properties of the basal plane. This indicates that black phosphorus belongs to a group of materials known as topological insulators. Consequently, these effects render the magnetic properties highly anisotropic, as both diamagnetic and paramagnetic behavior can be observed depending on the orientation in the magnetic field. 相似文献
A new complex [Zn(NIT-1'-MeBzIm)Cl2(H2O)] (NIT-1'-MeBzIm = 2-{2'-[(l'- methyl)benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been prepared and structurally characterized by X-ray diffraction method. Crystal data: monoclinic, space group P21/n, Z = 4, C15H21Cl2N4O3Zn, Mr = 441.63, a = 7.2225(10), b = 30.849(4), c = 8.8758(13) , β = 103.904(2)°, V = 1919.6(5) 3, Dc = 1.528 g/cm3, μ(MoKα) = 1.579 mm1, F(000) = 908, R = 0.0436 and wR = 0.1029 for 2456 observed reflections with I > 2σ(I). X-ray analysis reveals that the Zn(II) ion is four-coordinated with a distorted tetrahedron. There also exist H-bonds, π-π piling interactions and weak intermolecular contacts between the NO groups which form a mutual stagger 3-D network configuration. Magnetic investigation reveals that there exists intermolecular antiferro- and ferromagnetic interactions in the title complex. 相似文献
A novel compound, (IBzQI)(TCNQ)2 2 (IBzQ1=1-(4-iodobenzyl)quinolinium and TCNQ = 7,7,8,8-tetracyanoquinodimethane) has been fabricated and X-ray single-crystal structurally analyzed. This compound crystallizes in the triclinic system, space group P1 with a = 8.3540(17), b = 13.284(3), c = 16.185(3) А, α= 82.12(3), β= 75.19(3), γ= 72.34°, V = 1651.2(6) А^3, Z= 2, C_40H_21IN_9, Mr = 754.56, Dc = 1.518 g/cm^3,μ= 1.015 mm^-1, S = 1.010, F(000) = 754, R = 0.0387 and wR = 0.0948. The structure analysis shows that the anions are stacked into column with tetrads, and there are two types of TCNQ entries (TCNQ-1 and TCNQ^0) in agreement with the IR spectra analysis of the compound. The temperature dependence of the magnetic susceptibility (2-300 K) for 2 exhibits spin gap of singlet-triplet feature, and the best fit gave △/kB = 1523.4 K. In order to understand both magnetic behavior and local charge distribution of [(TCNQ)2]-unit, the molecular orbital calculations and analysis based on extended Hückel method were performed, and the results support the analyses of both crystal structure and IR spectra. 相似文献