Cyclic [Cu-biRadical] Secondary Building Unit in 2p-3d and 2p-3d-4f Complexes: Crystal Structure and Magnetic Properties.

Employing the new nitronyl nitroxide biradical ligand biNIT-3Py-5-Ph (2-(5-phenyl-3-pyridyl)-bis(4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide)), a 16-spin Cu-radical complex, [Cu(biNIT-3Py-5-Ph)(hfac)] , and three 2p-3d-4f chain complexes, {[Ln(hfac)][Cu(hfac)](biNIT-3Py-5-Ph)} (Ln= Gd , Tb , Dy ; hfac = hexafluoroacetylacetonate), have been prepared and characterized. X-ray crystallographic analysis revealed in all derivatives a common cyclic [Cu-biNIT] secondary building unit in which two bi-NIT-3Py-5-Ph biradical ligands and two Cu ions are associated via the pyridine N atoms and NO units. For complex , two such units assemble with four additional Cu ions to form a discrete complex involving 16 = 1/2 spin centers.

Slow magnetic relaxation in a Dy triangle and a bistriangular Dy cluster.

Two lanthanide single-molecule magnets (SMMs) [Dy(μ-OH)(HL-1)(HO)](NO)·3HO (1, HL-1 = ()-3-(((8-hydroxyquinolin-2-yl)methylene)amino)propane-1,2-diol) and [Dy(μ-OH)(HL-2)(HL-2)(L-2)] (2, HL-2 = ()-2-hydroxy-'-(2-hydroxy-3-methoxybenzylidene)benzohydrazide) were synthesized and characterized structurally and magnetically. Complex 1 contains a triangular Dy core in which the three Dy ions share a μ-OH anion and the deprotonated ligands of (HL-1) serve both capping and bridging functions, while 2 displays a centrosymmetric hexanuclear Dy structure with two similar Dy triangular cores ligated by two fully deprotonated (L-2) ligands, each of which shares two μ-OH anions. All the Dy ions are eight-coordinated with quasi or symmetry.

Supramolecular heptanuclear Ln-Cu complexes involving nitronyl nitroxide biradicals: structure and magnetic behavior.

Four novel heptanuclear Ln-Cu complexes with the formula [LnCu(hfac)(NITPhTzbis)][LnCu(hfac)(NITPhTzbis)] (LnCu = YCu 1, TbCu 2, DyCu 3 and HoCu 4; hfac = hexafluoroacetylacetonate) were successfully constructed by employing the triazole functionalized nitronyl nitroxide biradical ligand NITPh-Tzbis (NITPh-Tzbis = 5-(1,2,4-triazolyl)-1,3-bis(1'-oxyl-3'-oxido-4',4',5',5'-tetramethyl-4,5-hydro-1-imidazol-2-yl)benzene). These hetero-tri-spin complexes are composed of two biradical-bridged dinuclear [(LnCu(hfac)(NITPhTzbis)] units and one trinuclear [LnCu(hfac)(NITPhTzbis)] unit which form a heptanuclear supramolecular structure through π-π interactions. Magnetic susceptibility investigations indicate that ferromagnetic exchange interactions dominate at low temperature for this supramolecular system which can be attributed to the Ln-nitroxide exchange and intramolecular NIT⋯NIT coupling mediated by the -phenylene moiety.

Improved single-chain-magnet behavior in a biradical-based nitronyl nitroxide-Cu-Dy chain.

A biradical with ferromagnetic intramolecular interaction was found to improve the SCM behavior of a nitronyl nitroxide-Cu-Dy chain, resulting in an energy barrier for magnetization reversal of 40 K.

Tuning Magnetic Relaxation in a Tb-Nitronyl Nitroxide Complex by Using Cocrystalline Paramagnetic Complex.

New 2p-4f and 2p-3d-4f compounds [Tb(hfac)3(NIT-PhNO2)2]· 0.5C7H16 (1) and [Ln(hfac)3(NIT-PhNO2)2]2[Cu(hfac)2(NIT-PhNO2)2] (Ln(III) = Gd 2, Tb 3; hfac = hexafluoroacetylacetonate; NIT-PhNO2 = 2-(p-nitrophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) have been obtained. Complex 1 consists of mononuclear trispin [Tb(hfac)3(NIT-PhNO2)2] units in which two radical ligands are ligated to the Tb(III) ion as monodentate ligands through the NO groups, while complexes 2 and 3 contain two kinds of trispin moieties, namely, [Ln(hfac)3(NIT-PhNO2)2] and [Cu(hfac)2(NIT-PhNO2)2].

Three-dimensional frameworks based on dodecanuclear Dy-hydroxo wheel cluster with slow relaxation of magnetization.

Two new heterometallic coordination polymers, [Na4Ln12(stp)8(OH)16(H2O)12]·10H2O [Ln = Dy (1) and Ho (2)], have been prepared from monosodium 2-sulfoterephthalate (NaH2stp), dysprosium acetate, or holmium acetate. They are isostructural, possessing a [Ln12(μ3-OH)16](20+) wheel-cluster core based on four vertex-sharing cubane-like [Ln4(μ3-OH)4](8+) units. The Ln12 cores are linked by stp ligands into a three-dimensional (3D) architecture.

Construction of nitronyl nitroxide-based 3d-4f clusters: structure and magnetism.

Three unprecedented nitronyl nitroxide radical-bridged 3d-4f clusters, [Ln2 Cu2 (hfac)10 (NIT-3py)2 (H2 O)2 ](Ln(III) =Y, Gd, Dy), have been obtained from the self-assembly of Ln(hfac)3 , Cu(hfac)2 , and the radical ligand. The Dy complex shows a slow relaxation of magnetization, representing the first nitronyl nitroxide radical-based 3d-4f cluster with single-molecule magnet behavior.

Unprecedented nitronyl nitroxide bridged 3d-4f complexes: structure and magnetic properties.

Two novel 2p-3d-4f compounds, {Ln(hfac)3[Cu(hfac)2]3(NITPhPyrim)2} [Ln = Gd (1), Dy (2)], have been obtained by reacting phenyl pyrimidyl nitronyl nitroxide with Cu(hfac)2 and Ln(hfac)3. These two compounds are the first examples of two-dimensional 3d-4f complexes bridged by nitronyl nitroxide radicals. Overall ferromagnetic behaviors were observed in both compounds.

Syntheses, structures, and magnetic and luminescence properties of a new Dy(III)-based single-ion magnet.

Three new Ln(III) complexes based on 2,2'-bipyridine [Ln(hfac)3(bpy)] (Ln = Dy (1), Tb (2), or Ho (3); hfac = hexafluoroacetylacetonate; and bpy = 2,2'-bipyridine) have been synthesized and characterized structurally and magnetically. Single-crystal X-ray analysis shows that all these complexes contain one [Ln(hfac)3(bpy)] unit in which a center Ln(III) ion is surrounded with a slightly distorted square-antiprismatic LnO6N2 coordination sphere formed by three bischelate hfac anions and one bpy ligand. Both static and dynamic magnetic properties were studied for complex 1, which is proved to be a new single-ion magnet.

Modulating spin dynamics of cyclic LnIII-radical complexes (LnIII = Tb, Dy) by using phenyltrifluoroacetylacetonate coligand.

Three novel ring-like compounds formulated as [Ln(Phtfac)(3)(NITpPy)](2) (Ln(III) = Gd 1, Tb 2, Dy 3; HPhtfac = 4,4,4-trifluoro-1-phenylbutane-1,3-dione; NITpPy = 2-(4-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl-3-oxide) were synthesized and structurally and magnetically characterized. Three compounds possess cyclic dimer structure in which each pyridine substituted radical links two different metal ions through the oxygen of nitroxide group and the pyridine nitrogen. DC magnetic studies show the Ln(III) ion interacts ferromagnetically with the directly bonding nitronyl nitroxide.

Self-assembly, crystal structures, and properties of metal-2-sulfoterephthalate frameworks based on [M4(μ3-OH)2]6+ clusters (M = Co, Mn, Zn and Cd).

Hydro- and solvo-thermal reactions of d-block metal ions (Mn(2+), Co(2+), Zn(2+) and Cd(2+)) with monosodium 2-sulfoterephthalate (NaH(2)stp) form six 3D coordination polymers featuring cluster core [M(4)(μ(3)-OH)(2)](6+) in common: [M(2)(μ(3)-OH)(stp)(H(2)O)] (M = Co (1), Mn (2) and Zn (3)), [Zn(2)(μ(3)-OH)(stp)(H(2)O)(2)] (4), [Zn(4)(μ(3)-OH)(2)(stp)(2)(bpy)(2)(H(2)O)]·3.5H(2)O (5) and [Cd(2)(μ(3)-OH)(stp) (bpp)(2)]·H(2)O (6) (stp = 2-sulfoterephthalate, bpy = 4,4'-bipyridine and bpp = 1,3-di(4-pyridyl)propane). All these coordination polymers were characterized by single crystal X-ray diffraction, IR spectroscopy, thermogravimetric and elemental analysis.

Ligand field-tuned single-molecule magnet behaviour of 2p-4f complexes.

Three new 2p-4f complexes of [Ln(acac)(3)(NIT-2Py)]·0.5NIT-2Py [Ln(III) = Gd(1), Dy(2)] and [Dy(tfa)(3)(NIT-2Py)]·0.5C(7)H(16) (3) (NIT-2Py = 2-(2'-pyridyl)- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide; acac = acetylacetonate and tfa = trifluoroacetylacetonate) have been synthesized, and structurally and magnetically characterized.

Synthesis, structure and magnetic properties of a novel family of heterometallic nonanuclear Na(I)2Mn(III)6Ln(III) (Ln = Eu, Gd, Tb, Dy) complexes.

The structures and magnetic properties of four isomorphous nonanuclear heterometallic complexes [Na(2){Mn(3)(III)(μ(3)-O(2-))}(2)Ln(III)(hmmp)(6)(O(2)CPh)(4)(N(3))(2)]OH·0.5 CH(3)CN·1.5H(2)O are reported, where Ln(III) = Eu (1), Gd (2), Tb (3) and Dy (4), H(2)hmmp = 2-[(2-hydroxyethylimino)methyl]-6-methoxyphenol.

Self-assembly and characterization of copper 3,4-pyridinedicarboxylate complexes based on a variety of polynuclear hydroxo clusters.

Self-assembly of copper(ii) ion, 3,4-pyridinedicarboxylate (PDC), and 1,10-phenanthroline (phen) under basic conditions at 100 °C affords four PDC linked copper(ii) complexes, [Cu(4)(μ(2)-OH)(3)(μ(3)-OH)(PDC)(phen)(4)](n)·n(PDC)·11.5 nH2O (1), [Cu(4)(μ(2)-OH)(2)(μ(3)-OH)(2)(PDC)(phen)(4)](n)·n(PDC)· 11.5 nH(2)O (2), [Cu(8)(μ(2)-OH)(2)(μ(3)-OH)(6)(PDC)(2)(phen)(8)]·2(PDC)·23 H(2)O (3), and [Cu(3.

Slow magnetic relaxation in novel Dy4 and Dy8 compounds.

Two novel dysprosium(III) clusters have been prepared and structurally characterized. One has a tetranuclear core with a rare zigzag arrangement, and the other is an unprecedented octanuclear cluster with six triangular Dy(3) units sharing vertices. Both dysprosium(III) clusters possess frequency-dependent on alternating-current magnetic susceptibilities, indicating possible single-molecule magnet behavior.

Pyrazine-bridged Dy2 single-molecule magnet with a large anisotropic barrier.

Utilization of the strong electron-withdrawing ligand, hfac, leads to a novel dinuclear dysprosium single-molecule magnet featuring a pyrazine bridge with a large anisotropic barrier.

Syntheses, crystal structures and magnetic properties of a novel family of penta-manganese complexes derived from an assembly system containing polydentate hydroxy-rich Schiff-base ligands.

The syntheses, crystal structures, and magnetochemical characterization are reported of a novel family of four pentanuclear manganese complexes, namely, [Mn(III)(5)(mu(3)-O)(2)(L(1))(4)(O(2)CMe)(3)(CH(3)OH)].1.5CH(3)OH.

Slow magnetic relaxation in lanthanide complexes with chelating nitronyl nitroxide radical.

Two rare-earth radical complexes [Ln(hfac)(3)NIT-2Py].0.5C(7)H(16) [Ln = Tb (1), Dy (2)] have been synthesized and characterized structurally as well as magnetically.

A monometallic tri-spin single-molecule magnet based on rare earth radicals.

A mononuclear tri-spin single-molecule magnet based on the rare earth radical [Tb(hfac)3(NITPhOEt)2] (NITPhOEt = 4'-ethoxy-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been synthesized, structurally characterized and the alternating current signals show a slow relaxation of magnetization and frequency-dependent signals.

Four new lanthanide-nitronyl nitroxide (Ln(III) = Pr(III), Sm(III), Eu(III), Tm(III)) complexes and a Tb(III) complex exhibiting single-molecule magnet behavior.

Five new complexes based on rare-earth-radical [Ln(hfac)(3)(NIT-5-Br-3py)](2) (Ln = Pr (1), Sm (2), Eu (3), Tb (4), Tm (5); hfac = hexafluoroacetylacetonate; NIT-5-Br-3py = 2-(4,4,5,5-tetramethyl-3-oxylimidazoline-1-oxide)-5-bromo-3-pyridine) have been synthesized and characterized by X-ray crystal diffraction. The single-crystal structures show that these complexes have similar structures, in which a NIT-5-Br-3py molecule acts as a bridging ligand linking two Ln(III) ions through the oxygen atom of the N-O group and nitrogen atom from the pyridine ring to form a four-spin system. Both static and dynamic magnetic properties were measured for complex 4, which exhibits single-molecule magnetism behavior.

Hydrothermal reaction of Cu(II)/pyrazine-2,3,5-tricarboxylic acid and characterization of the copper(II) complexes.

Four copper(II) complexes [Cu3(PZHD)2(2,2'-bpy)2(H2O)2].3H2O (1), [Cu3(DHPZA)2(2,2'-bpy)2] (2), [Cu(C2O4)phen(H2O)].H2O (3), and [Cu3(PZTC)2(2,2'-bpy)2].

[Cu(L)Mn(N3)2]n: the first complex containing both macrocyclic oxamido and alternate (mu-1,1 and mu-1,3) azido bridges.

A wattle-type heteropolynuclear complex [(CuL)Mn(N(3))(2)](n) (1) (H(2)L = 2,3-dioxo-5,6:15,16-dibenzo-1,4,8,13-tetraazacyclo-pentadeca-7,13-diene), which represents the first system with macrocyclic oxamido and alternate azido bridges, forming a one-dimensional chain structure, has been synthesized and characterized by a low temperature magnetic study. The chains are stacked with interchain hydrogen and lead to the structure of a three-dimensional network.