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Coupling Interactions (coupling + interaction)
Selected AbstractsA Theoretical Study of the Nearest Cu···Cu Antiferromagnetic Exchange Coupling Interactions in [LaCu6] and [YCu6]EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2007Yi-Quan Zhang Abstract A density functional study of the exchange coupling interactions between the two nearest CuII centers in [LaCu6] and [YCu6] is presented. Two approaches show that the Cu···Cu antiferromagnetic interactions increase with a decrease of the ionic radius of the diamagnetic central LaIII and YIII ions. However, the influence of the central ions on the Cu···Cu interactions is small compared to that of their structures according to our calculations. We therefore conclude that the stronger antiferromagnetic interactions between the two nearest CuII centers in [LaCu6] than in [YCu6] are not a result of the central LaIII ion but the structure. The antiferromagnetic contributions of the direct overlap between the two nearest CuII magnetic orbitals also play a major role according to the calculations of the overlap integral Sij based on Kahn's theory.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis, structures and magnetic properties of a series of polynuclear copper(II)-lanthanide( III) complexes assembled with carboxylate and hydroxide ligandsCHINESE JOURNAL OF CHEMISTRY, Issue 5 2000Xiao-Ming Chen Abstract Heterometallic copper(II)-lanthanide(III) complexes have been made with a variety of exclusively O -donor ligands including betaines (zwitterionic carboxylates) and chloroacetate, which are dinuclear CuLn, tetranuclear Cu2Ln2, pentanuclear Cu3Ln2, and octadecanuclear Cu12 complexes. The results show that subtle changes in both the carboxylates and acidity of the reaction solution can cause drastic changes in the structures of the products. Magnetic studies exhibit that shielding of the Ln3+ 4f electrons by the outer shell electrons is very effective to preclude significant coupling interaction between the Ln3+ 4f electrons and Cu2+ 3d electrons in either a mono-atomic hydroxide-bridged, or a carboxylate-bridged system. [source] Two Hexanickel-Substituted Keggin-Type Germanotungstates,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 24 2008Jun-Wei Zhao Abstract Two new inorganic,organic hybrid germanotungstates built from trivacant Keggin fragments and in situ generated hexanickel clusters [Ni(en)2]0.5[{Ni6(,3 -OH)3(en)3(H2O)6}(B-,-GeW9O34)]·3H2O (1) and [{Ni6(,3 -OH)3(dap)3(H2O)6}(B-,-GeW9O34)]·H3O·4H2O (2) (en = ethylenediamine and dap = 1,2-diaminopropane) were hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, single-crystal X-ray diffraction and magnetic analysis. Compound 1 crystallizes in the monoclinic space group P21/n; whereas compound 2 crystallizes in the monoclinic space group P21/c. Single-crystal X-ray diffraction indicates that both contain a hexa-NiII -substituted trivacant Keggin unit [{Ni6(,3 -OH)3(L)3(H2O)6}(B-,-GeW9O34)], (L = en or dap). Magnetic susceptibility measurements show the presence of ferromagnetic coupling interactions within the hexa-NiII clusters for 1 and 2. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] A Theoretical Study of the Nearest Cu···Cu Antiferromagnetic Exchange Coupling Interactions in [LaCu6] and [YCu6]EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2007Yi-Quan Zhang Abstract A density functional study of the exchange coupling interactions between the two nearest CuII centers in [LaCu6] and [YCu6] is presented. Two approaches show that the Cu···Cu antiferromagnetic interactions increase with a decrease of the ionic radius of the diamagnetic central LaIII and YIII ions. However, the influence of the central ions on the Cu···Cu interactions is small compared to that of their structures according to our calculations. We therefore conclude that the stronger antiferromagnetic interactions between the two nearest CuII centers in [LaCu6] than in [YCu6] are not a result of the central LaIII ion but the structure. The antiferromagnetic contributions of the direct overlap between the two nearest CuII magnetic orbitals also play a major role according to the calculations of the overlap integral Sij based on Kahn's theory.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Great Framework Variation of Polymers in the Manganese(II) Maleate/,,,,-Diimine System: Syntheses, Structures, and Magneto-Structural CorrelationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2003Chengbing Ma Abstract Three novel manganese(II) coordination polymers, [Mn (maleate)(phen)]n (1; phen = 1,10-phenanthroline), [Mn(maleate)(phen)]n·nH2O (2), and [Mn(maleate)(bpy)]n (3; bpy = 2,2,-bipyridine), have been synthesized by treatment of Mn2+ with maleic acid with participation of chelate diimine ligands, and have been identified by single-crystal X-ray diffraction to have either one-dimensional (1D) zigzag chain structures (1 and 2) or a two-dimensional (2D) sinuous layer structure (3). Each maleate dianion coordinates to three Mn centers, in different bridging modes (syn - anti in 1 and 2, syn - syn and anti - anti in 3). These compounds represent an interesting example of structural topology variation from 1D to 2D mediated by chemically similar auxiliary chelate ligands. Variable-temperature magnetic susceptibility measurements show weak anti-ferromagnetic exchange interactions between the adjacent MnII ions, with J = ,0.06 cm,1 (2) and J = ,1.3 cm,1, zJ, = ,0.27 cm,1 (3). The differences in the magnitudes of these coupling interactions agree well with the nature of the carboxylate-bridging coordination of maleate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] SESAME-HSQC for simultaneous measurement of NH and CH scalar and residual dipolar couplings,MAGNETIC RESONANCE IN CHEMISTRY, Issue 4 2007Peter Würtz Abstract We present a novel pulse sequence, SESAME-HSQC, for the simultaneous measurement of several NH and CH scalar and residual dipolar couplings in double labeled proteins. The proposed Spin-statE Selective All Multiplicity Edited (SESAME)-HSQC combines gradient selected and sensitivity enhanced 15N- and constant-time 13C-HSQC experiments with the recently introduced spin-state selective method (Nolis et al., J. Magn. Reson. 180 (2006) 39,50) for measuring couplings simultaneously at amide and aliphatic regions. Excellent resolution and high sensitivity is warranted by removing all coupling interactions during the indirectly detected t1 period, and by employing pulsed field gradients for coherence selection and utilizing coherence order selective spin-state selection. The scalar and residual dipolar couplings can be readily measured from a two-dimensional 15N/13C-HSQC spectrum without additional spectral crowding. SESAME-HSQC can be used for epitope mapping by observing chemical shift changes in both amide and aliphatic regions. Simultaneously, potential conversion in protein conformation can be probed by analyzing changes in residual dipolar couplings induced by ligand binding. The pulse sequence is experimentally verified with a sample of 15N/13C enriched human ubiquitin. The internuclear vector directions determined from the residual dipolar couplings are found to be in excellent correlation with those predicted from ubiquitin's refined solution structure. Copyright © 2007 John Wiley & Sons, Ltd. [source] Self-Assembly of [B -SbW9O33]9, Subunit with Transition Metal Ions (Mn2+, Cu2+, Co2+) in Aqueous Solution: Syntheses, Structures and Magnetic Properties of Sandwich Type Polyoxometalates with Subvalent SbIII HeteroatomCHEMISTRY - AN ASIAN JOURNAL, Issue 5 2008Jing-Ping Wang Prof. Abstract Rational self-assembly of Sb2O3 and Na2WO4, or (NH4)18[NaSb9W21O86] with transition-metal ions (Mn2+, Cu2+, Co2+), in aqueous solution under controlled conditions yield a series of sandwich type complexes, namely, Na2H2[Mn2.5W1.5(H2O)8(B -,-SbW9O33)2],32,H2O (1), Na4H7[Na3(H2O)6Mn3(,-OAc)2(B -,-SbW9O33)2],20,H2O (OAc=acetate anion) (2), NaH8[Na2Cu4Cl(B -,-SbW9O33)2],21,H2O (3), Na8K[Na2K(H2O)2{Co(H2O)}3(B -,-SbW9O33)2], 10,H2O (4), and Na5H[{Co(H2O)2}3W(H2O)2(B -,-SbW9O33)2],11.5,H2O (5). These structures are determined by using the X-ray diffraction technique and further characterized by obtaining IR spectra and performing elemental analysis. Structure analysis reveals that polyoxoanions in 1 and 5 comprise of two [B -,-SbW9O33]9, building units, whereas 2, 3, and 4 consist of two isomerous [B -,-SbW9O33]9, building blocks, which are all linked by different transition-metal ions (Mn2+, Cu2+, or Co2+) with different quantitative nuclearity. It should be noted that compound 2 represents the first one-dimensional sinusoidal chain based on sandwich like tungstoantimonate building blocks through the carboxylate-bridging ligands. Additionally, 3 is constructed from sandwiched anions [Na2Cu4Cl(B -,-SbW9O33)2]9, linked to each other to form an infinitely extended 2D network, whereas 5 shows an interesting 3D framework built up from offset sandwich type polyoxoanion [{Co(H2O)2}3W(H2O)2(B -,-SbW9O33)2]6, linked by Co2+ and Na+ ions. EPR studies performed at 110,K and room temperature reveal that the metal cations (Mn2+, Cu2+, Co2+) reside in a square-pyramidal geometry in 2, 3, and 4. The magnetic behavior of 1,4 suggests the presence of weak antiferromagnetic coupling interactions between magnetic metal centers with the exchange integral J=,0.552,cm,1 in 2. [source] | ||||||||||