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1.
《Polyhedron》2003,22(14-17):2267-2271
The synthesis and structural characterization of the two new Mn complexes [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 (1) and [Mn21O16(O2CMe)16(hmp)6(hmpH)2(pic)2(py)(H2O)](ClO4)4 (3) are presented, together with a detailed study of their magnetic properties. Complex 1 possesses a ground-state spin of S=13, and the ground-state spin for 3 is estimated to be S=17/2 or 19/2. Both complexes 1 and 3 are new examples of single-molecule magnets (SMMs), displaying frequency-dependent out-of-phase AC signals, as well as magnetization vs. DC field hysteresis at temperatures below 1 K. Complex 1 straddles the classical/quantum interface by also displaying quantum tunneling of the magnetization (QTM). 相似文献
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Rumberger EM Shah SJ Beedle CC Zakharov LN Rheingold AL Hendrickson DN 《Inorganic chemistry》2005,44(8):2742-2752
The reaction of [Mn(12)O(12)(O(2)CCH(3))(16)(H(2)O)(4)].4H(2)O.2CH(3)COOH with n-methyldiethanol amine (H(2)mdea), n-ethyldiethanol amine (H(2)edea), or n-butyldiethanol amine (H(2)bdea) leads to the formation of wheel-shaped Mn(III)(6)Mn(II)(6) complexes with the general formula [Mn(12)(R)(O(2)CCH(3))(14)] (1, R = mdea; 2, R = edea; and 3, R = bdea). Complex 1 crystallizes in the triclinic space group P1, whereas complex 3 crystallizes in the monoclinic space group C(2/c). Complex 1a has the same molecular structure as complex 1 but crystallizes in the monoclinic space group P2(1/n). Complex 3a has the same molecular structure as complex 3 but crystallizes in the triclinic space group P1. Variable-temperature magnetic susceptibility data collected for complexes 1, 2, and 3 indicate that antiferromagnetic exchange interactions are present. The spin ground states of complexes 1, 2, and 3 were determined by fitting variable-field magnetization data collected in the 2-5 K temperature range. Fitting of these data yielded the spin ground-state parameters of S = 8, g = 2.0, and D = -0.47 cm(-1) for complex 1; S = 8, g = 2.0, and D = -0.49 cm(-1) for complex 2; and S = 8, g = 2, and D = -0.37 cm(-1) for complex 3. The ac magnetic susceptibility data were measured for complexes 1, 2, and 3 at temperatures between 1.8 and 10 K with a 3 G ac field oscillating in the range 50-1000 Hz. Slow kinetics of magnetization reversal relative to the frequency of the oscillating ac field were observed as frequency-dependent out-of-phase peaks for complexes 1, 2, and 3, and it can be concluded that these three complexes are single-molecule magnets. 相似文献
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Andreas G. Flamourakis Dimitris A. Kalofolias Milosz Siczek Tadeusz Lis 《Journal of Coordination Chemistry》2016,69(5):826-840
The synthesis, structural, and magnetic characterization of five new members of the hexanuclear oximate [MnIII6] family are reported. All five clusters can be described with the general formula [MnIII6O2(R-sao)6(R′-CO2)2(sol)x(H2O)y] (where R-saoH2 = salicylaldoxime substituted at the oxime carbon with R = H, Me and Et; R′ = 1-naphthalene, 2-naphthalene, and 1-pyrene; sol = MeOH, EtOH, or MeCN; x = 0–4 and y = 0–4). More specifically, the reaction of Mn(ClO4)2·6H2O with salicylaldoxime-like ligands and the appropriate carboxylic acid in alcoholic or MeCN solutions in the presence of base afforded complexes 1–5: [Mn6O2(Me-sao)6(1-naphth-CO2)2(H2O)(MeCN)]·4MeCN (1·4MeCN); [Mn6O2(Me-sao)6(2-naphth-CO2)2(H2O)(MeCN)]·3MeCN·0.1H2O (2·3MeCN·0.1H2O); [Mn6O2(Et-sao)6(2-naphth-CO2)2(EtOH)4(H2O)2] (3); [Mn6O2(Et-sao)6(2-naphth-CO2)2(MeOH)6] (4) and [Mn6O2(sao)6(1-pyrene-CO2)2(H2O)2(EtOH)2]·6EtOH (5·6EtOH). Clusters 3, 4, and 5 display the usual [Mn6/oximate] structural motif consisting of two [Mn3O] subunits bridged by two Ooximate atoms from two R-sao2? ligands to form the hexanuclear complex in which the two triangular [Mn3] units are parallel to each other. On the contrary, clusters 1 and 2 display a highly distorted stacking arrangement of the two [Mn3] subunits resulting in two converging planes, forming a novel motif in the [Mn6] family. Investigation of the magnetic properties for all complexes reveal dominant antiferromagnetic interactions for 1, 2, and 5, while 3 and 4 display dominant ferromagnetic interactions with a ground state of S = 12 for both clusters. Finally, 3 and 4 display single-molecule magnet behavior with Ueff = 63 and 36 K, respectively. 相似文献
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Taylor SM Karotsis G McIntosh RD Kennedy S Teat SJ Beavers CM Wernsdorfer W Piligkos S Dalgarno SJ Brechin EK 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(27):7521-7530
In the cone conformation calix[4]arenes possess lower-rim polyphenolic pockets that are ideal for the complexation of various transition-metal centres. Reaction of these molecules with manganese salts in the presence of an appropriate base (and in some cases co-ligand) results in the formation of a family of calixarene-supported [Mn(III)(2)Mn(II)(2)] clusters that behave as single-molecule magnets (SMMs). Variation in the alkyl groups present at the upper-rim of the cone allows for the expression of a degree of control over the self-assembly of these SMM building blocks, whilst retaining the general magnetic properties. The presence of various different ligands around the periphery of the magnetic core has some effect over the extended self-assembly of these SMMs. 相似文献
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The reactions of the ligands N-methyldiethanol amine and N-ethyldiethanol amine (abbreviated H(2)mdea and H(2)edea, respectively) with [Mn(12)O(12)(O(2)CCH(3))(16)(H(2)O)(4)] yield novel dodecanuclear wheel-shaped products. The capability of the ligands H(2)mdea and H(2)edea to support wheel structures in metals other than Mn is demonstrated with the crystal structure of a new hexanuclear ferric wheel. 相似文献
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Facile Interchange of 3d and 4f Ions in Single‐Molecule Magnets: Stepwise Assembly of [Mn4], [Mn3Ln] and [Mn2Ln2] Cages within Calix[4]arene Scaffolds 下载免费PDF全文
Dr. Maria A. Palacios Dr. Ross McLellan Dr. Christine M. Beavers Dr. Simon J. Teat Dr. Høgni Weihe Dr. Stergios Piligkos Dr. Scott J. Dalgarno Prof. Euan K. Brechin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(31):11212-11218
The central MnII ions in a series of calix[4]arene‐stabilised butterflies can be sequentially replaced with LnIII ions, maintaining the structural integrity of the molecule but transforming its magnetic properties. The replacement of MnII for GdIII allows for the examination of the transferability of spin‐Hamiltonian parameters within the family as well as permitting their reliable determination. The introduction of the 4f ions results in weaker intramolecular magnetic exchange, an increase in the number of low‐lying excited states, and an increase in magnetisation relaxation, highlighting the importance of exchange over single‐ion anisotropy for the observation of SMM behaviour in this family of complexes. The presence of the [TMII/III(TBC[4])(OH)(solvent)] metalloligand (TM=transition metal, TBC=p‐tBu‐calix[4]arene) suggests that magnetic calix[n]arene building blocks can be employed to encapsulate a range of different “guests” within structurally robust “hosts”. 相似文献
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Alexander Ovchinnikov Dr. Matej Bobnar Dr. Yurii Prots Dr. Horst Borrmann Dr. Jörg Sichelschmidt Prof. Yuri Grin Dr. Peter Höhn 《Angewandte Chemie (International ed. in English)》2018,57(36):11579-11583
Two new calcium nitridomanganates, Ca12[Mn19N23] (P3, a=11.81341(3) Å, c=5.58975(2) Å, Z=1) and Ca133[Mn216N260] ( , a=39.477(1) Å, c=5.5974(2) Å, Z=1), were obtained by a gas–solid reaction of Ca3N2 and Mn with N2 at 1273 K and 1223 K, respectively. The crystal structure of Ca12[Mn19N23] was determined from high‐resolution X‐ray synchrotron powder diffraction data, whereas single‐crystal X‐ray diffraction was employed to establish the crystal structure of the Ca133[Mn216N260] phase, which classifies as a complex metallic alloy (CMA). Both crystal structures have 2D nitridomanganate layers containing similar building blocks but of different levels of structural complexity. Bonding analysis as well as magnetic susceptibility and electron spin resonance measurements revealed that only a fraction of the Mn atoms in both structures carries a localized magnetic moment, while for most Mn species the magnetism is quenched as a result of metal–metal bond formation. 相似文献
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Bi Y Liao W Wang X Wang X Zhang H 《Dalton transactions (Cambridge, England : 2003)》2011,40(9):1849-1851
The calixarene-Mn(4)-calixarene dumbbell-like unit can accommodate different fullerenes with its changeable curved surfaces and the addition of fullerenes completely remodels the packing of the dumbbell units. 相似文献
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Moushi EE Lampropoulos C Wernsdorfer W Nastopoulos V Christou G Tasiopoulos AJ 《Inorganic chemistry》2007,46(10):3795-3797
A large [Mn10Na]4 loop-of-loops aggregate was prepared from the use of 1,3-propanediol (pdH2) in manganese carboxylate chemistry. It is constructed from four [Mn10(mu3-O)2(O2CMe)13(pd)6(py)2]- loops linked through Na+ ions and exhibits a saddlelike topology. Magnetic characterization showed that the Mn10 loop has an S approximately 4 ground-state spin and displays frequency-dependent in-phase and out-of-phase alternating current signals and also hysteresis loops that, however, are not typical of single-molecule magnets because of the existence of intermolecular interactions between the Mn10 units. 相似文献
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Milios CJ Manoli M Rajaraman G Mishra A Budd LE White F Parsons S Wernsdorfer W Christou G Brechin EK 《Inorganic chemistry》2006,45(17):6782-6793
The synthesis and magnetic properties of four new Mn complexes containing tripodal alcohol ligands are reported: [Mn6(OAc)6(H2tea)2(tmp)2].2MeCN (1.2MeCN), [Mn6(acac)4(OAc)2(Htmp)2(H2N-ep)2] (2), [Mn6(OAc)8(tmp)2(py)4].2py (3.2py), and [Mn6(OAc)8(thme)2(py)4].2py (4.2py) [H3tea, triethanolamine; H3tmp, 1,1,1-tris(hydroxymethyl)propane; H2N-H2ep, 2-amino-2-ethyl-1,3-propanediol; H3thme, 1,1,1-tris(hydroxymethyl)ethane]. All complexes are mixed-valent with a [Mn(III)2Mn(II)4] oxidation assignment and are constructed from four edge-sharing triangles but differ slightly in that complexes 1 and 2 display a [Mn(III)2Mn(II)4(mu2-OR)6(mu3-OR)4]4+ core, while complexes 3 and 4 feature [Mn(III)2Mn(II)4(mu2-OR)2(mu3-OR)4]8+ and [Mn(III)2Mn(II)4(mu2-OR)4(mu3-OR)4]6+ cores, respectively. dc and ac magnetic susceptibility studies in the 2-300 K range for complexes 1-4 reveal the presence of dominant antiferromagnetic exchange interactions, leading to ground states of S = 0 for 1 and 2, while complexes 3 and 4 display S = 4 ground states with D = -0.44 and -0.58 cm(-1), respectively. Single-molecule magnetism behavior was confirmed for 3 and 4 by the presence of sweep-rate and temperature-dependent hysteresis loops in single-crystal M vs H studies at temperatures down to 40 mK. Theoretical density functional calculations were used to evaluate the individual pairwise exchange interactions present, confirming the diamagnetic ground states for 1 and 2 and the S = 4 ground states for 3 and 4. 相似文献
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Taylor SM McIntosh RD Beavers CM Teat SJ Piligkos S Dalgarno SJ Brechin EK 《Chemical communications (Cambridge, England)》2011,47(5):1440-1442
Phosphinate ligands allow for the transformation of a calix[4]arene supported [Mn(III)(2)Mn(II)(2)] tetramer cluster motif into an unusual [Mn(III)Mn(II)](2) dimer of dimers; the clusters self-assemble in the crystal to form bi-layer arrays reminiscent of the typical packing of calixarene solvates. 相似文献
16.
One-dimensional coordination polymers of antiferromagnetically-coupled [Mn4] single-molecule magnets
Lecren L Roubeau O Li YG Le Goff XF Miyasaka H Richard F Wernsdorfer W Coulon C Clérac R 《Dalton transactions (Cambridge, England : 2003)》2008,(6):755-766
Reactions of the rhombic [MnII2 MnIII2 (hmp)6]4+ complex in acetonitrile with simple carboxylate ligands yield (i) three new isolated [Mn4] complexes, namely [Mn4(hmp)6(CH3COO)2(H2O)2](ClO4)2.4H2O (1), [Mn4(hmp)6(CCl3COO)2(H2O)2](ClO4)2 (2) and [Mn4(hmp)6(C6H5COO)2(H2O)2](ClO4)2.4CH3CN.2H2O (3) in the presence of either bulky carboxylate or of an excess of Mn(II) source; and (ii) two 1D arrangements of [Mn4] complexes connected through double syn-syn carboxylate bridges when using acetate and chloroacetate, namely {[Mn4(hmp)6(CH3COO)2](ClO4)2.H2O}n (4) and {[Mn4(hmp)6(ClCH2COO)2](ClO4)2.2H2O}n (5). The assembly of such building blocks can thus be controlled by an adequate choice of the bridging anion. As expected, the isolated [Mn4] complexes behave as Single-Molecule Magnets as shown by the study of their static and dynamic magnetic properties. Detailed magnetic studies both on polycrystalline samples and single crystals show that the chain compounds are isolated antiferromagnetic chains. The slow relaxation of their staggered magnetization has been studied thanks to finite-size effects induced by the intrinsic defects of the material 相似文献
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Shieh M Chen HS Yang HY Lin SF Ueng CH 《Chemistry (Weinheim an der Bergstrasse, Germany)》2001,7(14):3152-3158
The reactions of appropriate ratios of K2TeO3 and [Mn2(CO)10)] in superheated methanol solutions lead to a series of novel cluster anions [Te4Mn3(CO)10] (1), [Te2Mn3(CO)9]2- (2), [Te2Mn3(CO)9]- (3), and [Te2Mn4(CO)12]2- (4). When cluster 1 is treated with [Mn2(CO)10]/KOH in methanol, paramagnetic cluster 2 is formed in moderate yield. Cluster 2 is oxidized by [Cu(MeCN)4]BF4 to give the closo-cluster [Te2Mn3(CO)9]- (3), while treatment of 2 with [Mn2(CO)10]/KOH affords the closo-cluster 4. IR spectroscopy showed that cluster 1 reacted with [Mn2(CO)10] to give cluster 4 via cluster 2. Clusters 1-4 were structurally characterized by spectroscopic methods or/and X-ray analyses. The core structure of 1 can be described as two [Mn(CO)3] groups doubly bridged by two Te2 fragments in a mu2-eta2 fashion. Both [Mn(CO)3] groups are further coordinated to one [Mn(CO)4] moiety. Cluster 2 is a 49 e- species with a square-pyramidal core geometry. While cluster 3 displays a trigonal-bipyramidal metal core, cluster 4 possesses an octahedral core geometry. 相似文献
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A series of [Mn6O2(R1OH)4(sao)6(R2COO)2] complexes with terminal functional groups ( 1 : R1 = CH3, R2 = HO‐C6H4, 2 : R1 = C2H5, R2 = H2N‐C6H4, 3 : R1 = CH3, R2 = Cl‐C6H4, 4 : R1 = CH3, R2 = CH3S‐C6H4, 5 : R1 = CH3, R2 = I‐C6H4, 6 : R1 = CH3, R2 = pymSCH2, 7 : R1 = CH3, R2 = ortho‐pyr‐SCH3, 8 : R1 = C2H5, R2 = (CH3)3OOCNHCH2C6H4; sao = doubly deprotonated salicylaldoxime ligand, pym = pyrimidyl, pyr = pyridyl) have been obtained in a reaction of a ligand R2C6H4COOH, salicylaldoxime, manganese(II) perchlorate and [NEt4](OH) in methanol or a 1:1 mixture of ethanol and dichloromethane. In this report, structural aspects as well as preliminary studies of magnetic and thermal properties are presented. Compounds 1 , 3 , 6 , 8 exhibit an antiferromagnetic coupling of the Mn2+ ions, whereas 4 and 7 show ferromagnetic interactions. The title compounds may act as starting materials for further derivatization addressing the functional groups. 相似文献
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K6[Mn2O6] and K6[Fe2O6] - a Comparison K6[Mn2O6] has been prepared (dark-red single crystals). The structure (a = 8.886, b = 6.760, c = 11.394 Å, γ = 132.1°, space group P21, Z = 2, 1151 symmetry independent reflections hk0–hk9, R = 0.051) shows Al2Cl6-like anions [Mn2O6]6?. By unit-cell transformation to the monoclinic setting P21/a (a = 6.760, b = 11.394, c = 6.638 Å, β = 96,9°) the structural similarity to K6[Fe2O6] becomes evident. The Madelung Part of Lattice Energy, MAPLE, is calculated. 相似文献