ABSTRACT
Four tetranuclear 3d-4f complexes, namely [Fe2Ln2(L)2(teaH)2(Cl)2](NO3)2·4CH3CN (H2L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine, teaH3 = triethanolamine, Ln = Dy for 1 and Ln = Gd for 1') and [Co2Ln2(L)2(pdm)2(CH3COO)2(CH3OH)2](NO3)2·xCH3OH·yH2O (pdmH2 = 2,6-pyridinedimethanol, Ln = Dy, x = 5 and y = 2.5 for 2 and Ln = Gd, x = 6 and y = 1.5 for 2'), have been reported. Two FeIII and two DyIII in 1 formed a zigzag Fe1-Dy1-Dy1a-Fe1a arrangement with a Fe1-Dy1-Dy1a angle of 105.328(3)°. However, in contrast to 1, two CoIII and two DyIII ions in 2 formed a more linear Co1-Dy1-Dy1a-Co1a arrangement with a Co1-Dy1-Dy1a angle of 141.86(2)°. Additionally, two DyIII ions in 1 are eight-coordinated with a triangular dodecahedron geometry, while two DyIII ions in 2 adopt nine-coordination with a muffin geometry. Magnetic studies revealed slow magnetic relaxation behavior for 1, with an energy barrier Ea of 6.9 K. For 2, single molecule magnet behavior was presented under a zero dc field with an effective energy barrier Ueff of 64.0(9) K. Ab initio calculations for 1 and 2 indicate that compared to 2, complex 1 has a larger transversal magnetic moment of its ground Kramers doublets (KD) and a larger value of the tunnelling parameter (Δt) for the exchanged coupled ground state, which may result in poor single molecule magnet behavior for 1.
ABSTRACT
In this work, we report the syntheses, crystal structures and magnetic properties of three novel Zn-Ln mixed metal complexes, namely [Zn4Dy2(L1)2(L2)2(N3)2]Cl2·2H2O (1), [Zn4Tb2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (2), and [Zn4Gd2(L1)2(L2)2(Cl)2][ZnN3Cl3]·2H2O (3), in which L12- and L23- were formed from the ligand L [L = N1,N3-bis(3-methoxysalicylidene)diethylenetriamine] through in situ reactions. Interestingly, carbon dioxide in air was absorbed in the process of forming carbamate ligand L23-; this can be ascribed to the insertion of CO2 into M-N amide bonds. Moreover, 1 and 2 represent the first series of 3d-4f SMMs containing carbamate ligands by fixation of CO2 in air. Single-crystal X-ray diffraction analyses reveal that the crystal structures of 1 and 2 are anion-dependent, i.e., the apical positions of the two ZnII ions in 1 and 2 are occupied by an N atom of N3- and by Cl-, respectively. However, the topologies of 2 and 3 are similar. Two ZnII ions and one LnIII (Ln = Dy (1), Tb (2) and Gd (3)) form nearly linear trinuclear [Zn2Ln] units which are double-bridged by two L23- ligands. Magnetic studies reveal that two complexes show single molecule magnet behavior under a direct current (dc) field, with effective energy barriers (Ueff) of 30.66(5) K for 1 and 8.87(3) K for 2. Ab initio calculations reveal that the DyIII ions in 1 and the TbIII ions in 2 are axial in nature; however, a difference in the tunnel splitting of 1 and 2 leads to variation in the magnetization blockades of the two complexes. Theoretical calculations also indicate that the directions of the main magnetic axes severely deviate from the coordination atoms of the first spheres of DyIII and TbIII in 1 and 2; thus further results in poor SMM behavior of the two complexes.
ABSTRACT
A pair of enantiopure mononuclear dysprosium/salen-type complexes (Et3NH)[Dy((R,R)/(S,S)-3-NO2salcy)2] (/), where 3-NO2salcyH2 represents N,N'-(1,2-cyclohexanediylethylene)bis(3-nitrosalicylideneiminato), are reported. The enantiomer contains two crystallographically independent dysprosium(iii) ions, each chelated by two enantiopure 3-NO2salcy(2-) ligands forming a [DyN4O4] core. Detailed magnetic studies on compound reveal a field-induced dual magnetic relaxation behavior, originating from single ion anisotropy and intermolecular interactions, respectively.
ABSTRACT
Reaction of (NBu3H)3[W(CN)8]·H2O and linear trinuclear complexes [Cu(II)2L2Ln(III)(NO3)3] (L = 2,6-di(acetoacetyl)pyridine, Ln = Eu (1), Gd (2), Tb (3) and Dy (4)) leads to the formation of four one-dimensional (1D) complexes. Single crystal X-ray analysis reveals that [W(CN)8](3-) bridges between the [Cu(II)2L2Ln(III)] sub-building units to construct the alternative chains. Magnetic investigation indicates that ferromagnetic interaction occurred between all paramagnetic ions and the slow magnetic relaxation properties were observed in complexes 3 and 4.
Subject(s)
Copper/chemistry , Lanthanoid Series Elements/chemistry , Organometallic Compounds/chemistry , Pyridines/chemistry , Tungsten Compounds/chemistry , Magnetic Phenomena , Models, Molecular , Organometallic Compounds/chemical synthesisABSTRACT
The first lanthanide mixed sulfate-sulfite inorganic coordination polymer, poly[diaqua-µ(4)-sulfato-di-µ(4)-sulfito-didysprosium(III)], [Dy(2)(SO(3))(2)(SO(4))(H(2)O)(2)](n), has been obtained, in which both sulfate and sulfite groups originate from the disproportionation of S(2)O(3)(2-) under hydrothermal and weakly acidic conditions. The crystal structure of the title compound exhibits a three-dimensional framework. The Dy(III) ion is surrounded by eight O atoms from one water molecule and two sulfate and five sulfite groups. These DyO(8) polyhedra have two shared edges and form an infinite zigzag Dy-O chain. In the bc plane, neighbouring chains are integrated through SO(3) trigonal pyramids, forming a two-dimensional sheet. Along the a-axial direction, the sulfate group, with the central S atom lying on a twofold axis, links adjacent two-dimensional sheets via two S-O-Dy connections, thus generating the three-dimensional framework.
ABSTRACT
Two polynuclear mixed-valence manganese clusters, [Mn(13)] and [Mn(16)], containing mixed chelating ligands were synthesized and structurally characterized. The alternating current (AC) susceptibilities of both complexes reveal nonzero frequency-dependent out-of-phase (χ(M)'') signals.
ABSTRACT
A series of asymmetric donor-acceptor substituted salen-type Schiff-bases have been synthesized and their structures, electronic properties and second order nonlinearities were investigated by DFT methods. In order to verify the stable of these Schiff-base derivates, the IR spectrum of these Schiff-base derivates were calculated, the result showed that these compounds are stable. The results of TD-DFT calculation indicate that the derivatives with the electron-donating group (CH3, OCH3 or N(C2H5)2) have a red shift absorption compared to derivatives with the electron-withdrawing group (NO2). The analysis of MOS indicates that the CN group has contribution to the LUMO orbital while the groups of OCH3, N(C2H5)2 and NO2 have contribution to the HOMO orbital. OCH3, N(C2H5)2 as electron rich groups, made the derivates have a larger first static hyperpolarizability. However, the compound (II) with a NO2 substituent, also has a large first static hyperpolarizability. This is probably because of the special transition model, namely the values of two oscillator strength f (fHOMO-1-LUMO=0.405, fHOMO-LUMO=0.321) are almost equal. In order to understand the influence of the energy gap (ΔE) between the HOMO and the LUMO orbitals on the first static hyperpolarizability, we calculated the energy gap (ΔE) of all Schiff-base compounds. The results show that the smaller the HOMO-LUMO energy gap is, the larger the first static hyperpolarizability is.
Subject(s)
Aldehydes/chemistry , Aldehydes/chemical synthesis , Electrons , Models, Chemical , Nonlinear Dynamics , Schiff Bases/chemistry , Schiff Bases/chemical synthesis , Azo Compounds/chemistry , Models, Molecular , Molecular Conformation , Spectrophotometry, Ultraviolet , Thermodynamics , Thiosemicarbazones/chemistryABSTRACT
Octacyanotungstate(V) reacts with Cu(NO(3))(2).2H(2)O and 1,4,7-trimethyl-1,4,7-triazacyclononane in methanol, resulting in an eicosanuclear cluster [Cu(13)W(7)], which shows a diamondoid shape with a Tolkowsky cut and bears intracluster ferromagnetic coupling.
ABSTRACT
In the title compound, [Mn(C(5)H(9)N(2)O(7)P(2))(2)(H(2)O)(2)], the Mn(II) atom (site symmetry ) is coordinated by four phos-pho-n-ate O atoms from a pair of partially deprotonated 1-hydr-oxy-2-(imidazol-3-yl)ethane-1,1-bis-phophonic acid ligands (imhedpH(3) (-)) and two water mol-ecules, resulting in a slightly distorted trans-MnO(6) octa-hedral geometry for the metal ion. In the ligands, the imidazole units are protonated and two of the hydr-oxy O atoms of the phospho-nate groups are deprotonated and chelate the Mn(II), thus forming the neutral mol-ecule of the title compound. The two protonated O atoms within the phospho-nate groups of one imhedpH(3) (-) ligand act as hydrogen-bond acceptors for a bifurcated hydrogen bond originating from the coordinated water mol-ecule. The phospho-nate units of neigboring mol-ecules are connected with their equivalents in neighboring mol-ecules via two types of inversion-symmetric hydrogen-bonding arrangements with four and two strong O-Hâ¯O hydrogen bonds, respectively. The two inter-actions connect mol-ecules into infinite chains along [111] and [110], in combination forming a tightly hydrogen-bonded three-dimensional supra-molecular network. This network is further stabilized by additional hydrogen bonds between the protonated imidazole units and one of the coordinated P-O O atoms and by additional O-Hâ¯O hydrogen bonds between the water mol-ecules and the P=O O atoms of neigboring mol-ecules.
ABSTRACT
The title compound, C(16)H(14)ClNOS, a potent anti-bacterial chemical, features a dihedral angle of 49.4â (1)° between the 4-tolyl and thia-zolidinone rings, and a dihedral angle of 87.2â (5)° between the thia-zolidinone and 4-chloro-phenyl rings.
ABSTRACT
The combination of redox and acid sites in lanthanide sulfonate leads to a potentially multifunctional catalyst for oxidation reactions. The title lanthanide sulfonate compound, [Yb(6)(CH(2)O(6)S(2))(4)O(OH)(8)(H(2)O)(6)](n), exhibits a novel one-dimensional columnar structure along the a direction. In the building unit of the columnar oligomer, a face-capped lanthanide octahedron, viz. [Ln(6)(mu(6)-O)(mu(3)-OH)(8)](8+), is found with an interstitial mu(6)-oxide group lying on an inversion centre, reports of which are rare in the literature. Adjacent hexameric cations are connected via two pairs of O-S-O bridges, thus forming a neutral column. The three-dimensional network is stabilized by an intricate pattern of intercolumnar hydrogen bonds.
ABSTRACT
The title compound, [Na(4)(CH(2)O(6)S(2))(2)(H(2)O)(5)](n), was crystallized from an aqueous solution. The sodium ions are surrounded and bridged by O atoms from coordinated water mol-ecules and sulfonate ions in a three-dimensional neutral network. The crystal structure is also stabilized by an intricate system of hydrogen bonds.
ABSTRACT
A cobalt diphosphonate Co(H(2)O){C(5)H(5)N-CH(2)CH(OH)(PO(3))(PO(3)H)} (1) has been synthesized under hydrothermal conditions. It shows a novel type of double chain structure in which one of the two CPO(3) terminus caps on top of the {Co(2)(micro-O)2} dimer while the other connects the adjacent {Co(2)(micro-O)2} dimers into a chain. The magnetization measurements reveal that dominant antiferromagnetic interactions are mediated between the magnetic centers and the compound experiences a field-induced magnetic transition at low temperature with H(c) of ca. 15 kOe at 1.8 K.