Synthesis,Structure and Magnetic Properties of a MnII Framework Assembled by Two Carboxylate Ligands

The 3D framework [Mn₃(CH₃COO)₂(HCOO)₄]_n · nDMF ( 1 ) was obtained from the assembly of Mn^II ions with acetate and the in‐situ generated formate ligands. It features Mn‐centered MnMn₄ tetrahedral nodes, each of which is linked to another four ones by sharing the apexes to form the 3D framework of 1 . Each of the acetate and formate ligands behaves as a syn‐syn:anti bridge to link two apical Mn^II ions and the central Mn^II ion. The magnetic measurement of 1 revealed the coexistence of spin‐canted antiferromagnetism and metamagnetism. It represents a typical example to synergistically use two kinds of carboxylate ligands to construct metal‐organic frameworks, as well as to tune the structure and magnetic properties of the aimed complex.     

Synthesis,Crystal Structure,Cryomagnetic Properties and Catalytic Activity for H2O2 Disproportionation of New Dinuclear and Polynuclear Bis(2,4-pentanedionate)manganese(II) Complexes with Diazine Ligands

The structures, magnetic properties, and catalytic activity for H₂O₂ disproportionation are reported for three new complexes [Mn₂(acac),(pydz)] ( 1 ), [Mn(acac)₂(pym)] ( 2 ), and (Mn(acac)₂(pyz)] ( 3 ) (acac = 2,4-pentanedionate, pydz = pyridazine, pym = pyrimidine, pyz = pyrazine). The X-ray crystal structures of 1 and 3 have been determined. Complex 1 crystallizes as a binuclear complex with η²-pyridazine and acac bridging ligands 3 crystallizes as a linear polymeric chain with bridging pyrazine molecule. Cryomagnetic investigations (4-300 K) reveal a weak intramolecular antiferromagnetic spin exchange with J = ?2.05, ?0.04, and ?0.05 cm^?1 for the complexes of 1, 2 , and 3 , respectively. The complexes 1–3 showed two-step catalytic activity for H₂O₂ disproportionation in pyridine solution at 0 °C.     

Synthesis and Properties of Complexes with Unusual {MnIII4} and {MnII4} Cages

Two types of manganese complexes with [Mn₄] cores featuring the unusual distorted cube topology are presented, the first of which comprises new modifications of the reported complex [Mn^III₄(sao)₄(saoH)₄]·3CHCl₃: [Mn₄(sao)₄(saoH)₄]·1.32(C₄H₁₀O)·0.43(CH₄O) ( 1a ) and [Mn(sao)₄(saoH)₄]·0.5(CH₄O)·0.5(C₂H₃N) ( 1b ) sao = salicylaldoxime. The second, 0.55[Mn₄Cl₄(C₁₂H₉N₂O)₄(CH₃OH)₂(H₂O)₂]·0.45[Mn₄Cl₄(C₁₂H₉N₂O)₄(CH₃OH)₄] ( 2 ), is the first reported case of a {Mn^II₄} core of this topology besides known {Mn^III₄} compounds. Differences between the {Mn^II₄} and {Mn^III₄} situation are discussed, and so far overlooked differences in magnetic properties between different {Mn^III₄} compounds are pointed out.     

Tetrachloroferrate(III) Complexes Containing Some Heteroaromatic Organic Cations: Structures and Magnetic Properties

The crystal structures of tetrachloroferrate(III) complexes having stoichiometry (BH)⁺ [FeCl₄]^? (where B = isoquinoline and 4‐aminopyridine) were determined at 100 K. While weak interactions, particularly N–H···Cl hydrogen bonds, are evident in the structures, distances between the Fe(III) centers are quite long in both cases. The structure of the compound with B = quinoline was compared with that previously established at room temperature, and showed that neither solid‐solid nor magnetic phase transitions occurred in this temperature range. Magnetic measurements on the paramagnetic powders indicate weak antiferromagnetic interactions transmitted through the crystal lattice, giving rise to Néel temperatures that are significantly below 10 K. Comparisons are made with other characterized [FeCl₄]^? compounds having similar organic base cations, enabling clarification of the superexchange mechanism.     

Synthesis,Structure, and Magnetic Properties of a Mn4 Cluster derived from Benzimidazole‐Alcohol Ligands

The synthesis, crystal structure, and magnetic properties of a [Mn^III₃Mn^II(μ₃‐O)(mbp)₃(OAc)₃] · 4H₂O ( 1 ) [H₂mbp = 2‐(1H‐benzimidazol‐2‐yl)‐2‐ methylpropane‐1,3‐diol] cluster are reported herein. Mn ions in compound 1 have a tetrahedron topology. Solid‐state direct current and alternating current magnetic susceptibility measurements on compound 1 reveal a ground state with S_T = 7/2 as well as the probable single‐molecule magnetic behavior.     

A Novel Ruthenium(III) and Lithium Complex: Synthesis,Crystal Structure,and Magnetic Properties

A novel complex [Li₃{μ‐(H₂O)₆}(H₂O)₆]·[RuCl₆] has been synthesized and was characterized by single‐crystal X‐ray diffraction. The compound crystallizes in rhombohedral space group R3¯c, with the unit cell parameters a = b = 9.948(2)Å, c = 33.376(14)Å, γ = 120°, V = 2860.5(15)ų, Z = 6, D_c = 1.918 Mg m^—3, μ = 1.703 mm^—1, R = 0.0244, wR = 0.0478. The compound consists of a cation, which contains three lithium ions linked by six bridged water molecules, and an anion, which contains a ruthenium(III) ion. The whole complex can be described as a three‐dimensional structure linked by hydrogen bonds between cation and anion. The magnetic properties of the complex have been investigated. The IR, UV‐vis and EPR spectra are studied.     

Diethylenetriammonium Aquapentachloroferrate(III) Chloride: Structure and Magnetic Properties

Diethylenetriamine (dien) and iron(III) chloride in aqueous HCl yield (dienH₃) [FeCl₅(H₂O)]Cl, in which the chloroferrate(III) anion is significantly distorted from octahedral symmetry due to the extensively hydrogen‐bonded lattice. On cooling, the high spin Fe^III material shows weak antiferromagnetic coupling that results in a Néel temperature of 2.70 K.     

Synthesis,Crystal Structures,and Magnetic Properties of Two Tetrahedral MnIIMnIII3 Complexes

Two tetranuclear manganese complexes, [NaMn^IIMn₃^III(μ₄‐O^2–)(HL)₃(SCN)₄] ( 1 ) and [NaMn^IIMn₃^III(μ₄‐O^2–)(HL)₃Cl₄][NaMn^IIMn₃^III(μ₄‐O^2–)(HL)₃Cl₃(H₂O)]ClO₄ · 3.5H₂O ( 2 ) were obtained from the reaction of manganese perchlorate with a quadridentate Schiff base ligand, 3‐(2‐hydroxybenzylideneamino)propane‐1, 2‐diol (H₃L) derived from condensation of 2‐hydroxybenzaldehyde with 3‐amino‐1, 2‐propanediol, as well as the coligand KSCN or NaCl under basic conditions. Single‐crystal X‐ray studies reveal that those two complexes all have a mixed‐valent tetrahedral core, which contains an apical Mn^II ion and three basal Mn^III ions situated in the [Mn₃(μ₄‐O^2–)]⁷⁺ equilateral triangle plane. Fitting of the magnetic susceptibility data to the theoretical χ_mT vs. T expression, revealed that the presence of only antiferromagnetic interactions between the central metal atoms in 1 , while both antiferromagnetic and ferromagnetic interactions are present in 2 .     

The Syntheses,Structures, and Magnetic Properties of Four 2D Lanthanide(III)‐naphthalenedicarboxylic Complexes

Four Ln‐NDC coordination polymers [Ln(NDC)(HNDC)(H₂O)] (Ln = La ( 1 ), Pr ( 2 ), Nd ( 3 ), Sm ( 4 ), H₂NDC = 1,4‐naphthalenedicarboxylic acid) were hydrothermally synthesized and structurally characterized by elemental analyses, IR spectroscopy, and single‐crystal X‐ray diffraction. Compounds 1 – 4 are isomorphous, and their structures display a layer constructed from a Ln‐organic chain and NDC^2– ligand, in which the H₂NDC ligands adopt two different acidity‐dependent types and coordination modes: HNDC^1– with μ‐η¹:η¹ and NDC^2– with μ‐η¹:η²:η¹:η². The 3D supramolecular networks of 1 – 4 are mainly controlled by hydrogen bonds interactions. The magnetic susceptibilities of complexes 2 – 4 reveal overall antiferromagnetic interactions between the Ln^III ions. In addition, thermogravimetric analysis of compound 2 is described.     

Structure and Magnetic Properties of a Dodecanuclear Twisted-Ring Iron(III) Cluster

An unprecedented nonplanar structure characterizes the complex [Fe(OCH₃)₂(dbm)]₁₂ (on the left in the picture), which contains the largest cyclic ferric cluster yet reported with chemically equivalent bridging units. It is made up of twelve high-spin, antiferromagnetically coupled iron(III ) centers and neatly reacts with Na^I or Li^I templates in organic solution to give hexairon(III ) coronates (right). Fe=•, O=○, NaI or LiI=• Hdbm=dibenzoylmethane.     

Synthesis,structure, and catalase-like activity of a novel manganese(II) complex: Dichloro[1,3-bis(2′-benzimidazolylimino)isoindoline]manganese(II)

Reaction of the ligand 1,3-bis(2′-benzimidazolylimino)isoindoline with manganese(II) chloride in acetonitrile/methanol leads to the novel mononuclear manganese(II) complex 1,3-bis(2′-benzimidazolylimino)isoindolinedichloro manganese(II) [Mn(bimindH)Cl₂], which has been characterized by various techniques such as elemental analysis, IR, UV–Vis, ESR spectroscopy, and X-ray diffraction. The ligand bimindH was synthesized by fusing phthalonitrile and 2-aminobenzimidazole at high temperature until ammonia evolution ceased. The catalase-like activity of the complex was tested in propionitrile, and it proved to be active in the dihydrogen peroxide dismutation. Based on kinetic studies the reaction is first-order in relation to both the complex and hydrogen peroxide.     

Crystal Structure and Magnetic Properties of a Hexanuclear Copper(II) Carboxylate

The synthesis and characterisation of the hexanuclear copper(II) carboxylate complex [Cu(O₂CCHPhOC₂H₄OC₂H₄OCH₃)₂]₆ ( 1 ) is described. Single‐crystal X‐ray structure analysis reveals that the copper(II) ions are arranged in a six‐membered ring which adopts a chair‐like conformation. The copper(II) ions are bridged by μ₂‐ and μ₃‐coordinating carboxylates. The magnetic behavior of 1 was measured between 2 and 300 K, revealing at low temperature a weak antiferromagnetic interaction. The χ_M(T) dependency was fitted mathematically with one coupling constant J₁ and a paramagnetic impurity α.     

Two Manganese(II) Complexes with a Bulky Fluorene‐Based Carboxylate Ligand: Syntheses,Crystal Structures,and Luminescent Properties

To explore the coordination possibilities of fluorene‐based ligands, two manganese(II) complexes with the ligand 9,9‐dibutyl‐9H‐fluorene‐2,7‐carboxylate ( L ) were synthesized and characterized: [Mn₂( L )₂(DMF)₃]_∞ ( 1 ) and [Mn₂( L )₂(DMF)]_∞ ( 2 ). X‐ray single‐crystal diffraction analyses show that complex 1 has a two‐dimensional (2D) (4,4) structure, whereas complex 2 consits of a three‐dimensional (3D) (4,5)‐connected topology framework. The results indicate that the steric bulk of the fluorene ring in H₂ L plays an important role in the formations of 1 and 2 . Additional pyridine‐based ligands govern the formation of the final frameworks of 2 . Moreover, the luminescent properties of these complexes were briefly investigated.     

Synthesis,Structure, Magnetic Properties,and Catalase‐like Activity of Methoxy‐bridged Manganese(III) Coordination Polymer containing Hydrazone based (O,N,O)2‐Donor Ligand

A 1D coordination polymer of manganese(III) with a hydrazone‐based ligand, [Mn₂(L)(μ‐OCH₃)₂(OHCH₃)₂]_n ( 1 ), was synthesized and characterized by elemental analyses and spectroscopic methods {H₄L = bis[(2‐hydroxynaphthalen‐1‐yl)methylene]adipohydrazide}. The crystal structure of 1 was determined by X‐ray crystallography. The two dianionic domains of the ligand adopt trans configuration, and each coordinates in a tridentate mode via the O, N, O′‐donor atoms to a Mn^III ion forming a dinuclear compound. The methoxy ligands provide an asymmetric bridge between two central manganese atoms, which lead to the formation of a 1D coordination polymer. A 2D supramolecular structure is formed by hydrogen bonding interactions between the 1D chains. Although the methoxy ligands are labile, the polymer preserves its oligonuclearity in the solution. Temperature‐dependent magnetic susceptibility studies proved the presence of a weak antiferromagnetic interaction between manganese(III) ions with J = –3.2 cm^–1, which results from axial distortion of the manganese coordination environment. Compound 1 showed catalase‐like activity in disproportionation of H₂O₂.     

Synthesis,Crystal Structure and Magnetic Properties of Zinc (II) Chloride Complexes with Pyridyl‐Substituted Nitronyl Nitroxides

ZnCl₂(NIT‐pPy) 1 , (NIT‐pPy = 2‐(4‐pyridyl)‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazolyl‐1‐oxyl‐3‐oxide) crystallizes in the orthorhombic space group Pnn2 with the cell parameters a = 9.4083(9), b = 39.686(3), c = 7.4417(14) Å. ZnCl₂(NIT‐6M‐oPy) 2 , (NIT‐6M‐oPy = 2‐(6‐methyl‐2‐pyridyl)‐4,4,5,5‐tetramethyl‐4,5‐dihydro‐1H‐imidazolyl‐1‐oxyl‐3‐oxide) crystallizes in the monoclinic space group Pn with a = 7.377(2), b = 19.096(4), c = 11.853(2) Å, β = 95.65(3)°. The temperature dependence magnetic susceptibility of complex 1 revealed an intermolecular ferromagnetic exchange interaction. A simple spin‐polarization model has been used to justify the observed ferromagnetic exchange interaction between the spins of the radical NO group in complex 2 .     

Influence of Steric Hindrance of N‐Heterocyclic Ancillary Ligands on the Structure and Magnetic Properties of Manganese(II) Coordination Polymers

Three biphenyl‐3,5‐dicarboxylic acid (H₂ L ) based coordination polymers, namely, [Mn₃( L )₃(2,2′‐bpy)₂]_n ( 1 ), {[Mn( L )(phen)] · (MeOH)}_n ( 2 ), and [Mn( L )(dipt)]_n ( 3 ), (2,2′‐bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline, and dipt = 2,9‐dimethyl‐1,10‐phenanthroline) were synthesized and characterized by single‐crystal X‐ray diffraction and analyses of their magnetic properties. 1 is a trinuclear manganese structure with a 2D motifs, which can join by hydrogen bond bridges to give 3D supramolecular architectures. 2 has a dinuclear center forming a 1D supramolecular ladder chain. The mononuclear complex 3 displays 1D metal‐organic chains driven by μ₂‐ L linkers. Their structural differences were investigated, revealing that the influence of steric hindrance on the structures of acid‐based coordination polymers is realized through changing the N‐heterocyclic ancillaries of diverse steric hindrance. Obviously, with decreasing of the steric hindrance of the N‐donor ligand, complexes 1 – 3 show structures from 1D to 2D and mononuclear to multinuclear. Magnetic susceptibility measurements indicate that 1 and 2 have dominating antiferromagnetic couplings between metal ions, whereas compound 3 is paramagnetic.     

Three Nickel(II) and Zinc(II) Complexes with Two Novel Nitronyl Nitroxide Ligands: Syntheses,Crystal Structures,and Luminescent Properties

To explore the coordination abilities of nitronyl nitroxide ligands, two ligands substituted with quinoxaline ( L¹ ) and 2‐phenyl‐1, 2, 3‐triazole ( L² ) and their Ni^II and Zn^II complexes: Ni( L¹ )(hfac)₂ ( 1 ), Ni( L² )(hfac)₂ ( 2 ), and Zn( L² )(hfac)₂ ( 3 ) (hfac = hexafluoroacetylacetonate), were synthesized and characterized. X‐ray single‐crystal diffraction analysis shows that compound 1 has a mononuclear structure, which is further linked into a three‐dimensional (3D) supramolecular network by C–H ··· F hydrogen‐bonding, C–H ··· π, and π ··· π stacking interactions. Complexes 2 and 3 have similar mononuclear structures, which are further linked into one‐dimensional (1D) supramolecular chains by various intermolecular weak interactions, such as C–H ··· F hydrogen‐bonding, and π ··· π stacking interactions. The results indicate that the steric bulk of L¹ and L² and the existence of hexafluoroacetylacetonate (hfac) play important roles in controlling the formation of the final frameworks of complexes 1 – 3 . Moreover, the luminescent properties of the ligands and their complexes were investigated in detail.     

Tetrachloroferrate(III) Complexes of some Organic Diammonium Cations: Structures and Magnetic Properties

With aqueous acidic iron(III) chloride, the three diamines ethylenediamine (en), tetramethylethylenediamine (tmeda) and 4:4′‐tetramethyldiaminodiphenylmethane (ddmp) yield the aquapentachloroferrate(III) and a pair of [FeCl₄]^? Cl^? double salts, respectively. Their structures indicate that N–H···Cl hydrogen bonding is present, but the Fe···Fe distances are all quite long. The magnetic data show that, while all the materials display antiferromagnetic coupling on cooling, in none of the cases was any transition observed above 1.8 K.     

Zinc(II) and Nickel(II) Complexes Based on Schiff Base Ligands: Synthesis,Crystal Structure,Luminescent and Magnetic Properties

Three new phenolate oxygen bridged transition metal complexes [Zn₃(HL¹)₃(μ₃‐CH₃O)]·(ClO₄)₂(H₂O)₃ ( 1 ), [Ni₂(HL¹)₂(μ_1,1‐N₃)(o‐vanillin)]·H₂O ( 2 ), [Ni₃(HL²)₂(PhCOO)₂(PhCOOH)₂(EtOH)₂] ( 3 ) have been synthesized by metal ions and potentially multidentate Schiff base ligands (H₂L¹ = 2‐((1‐hydroxy‐2‐methylpropan‐2‐ylimino) methyl)‐6‐methoxyphenol; H₃L² = (E)‐1‐((2‐hydroxy‐3‐methoxy‐benzylidene)amino)ethane‐1,2‐diol). All the three complexes 1 , 2 , and 3 have been characterized by elemental analysis, FT‐IR spectroscopy, and single‐crystal X‐ray diffraction studies. Crystal structures reveal that complex 1 is a trinuclear incomplete cubane‐like zinc cluster whereas complex 2 is a dinuclear nickel complex bridged by azide, and compound 3 is a trinuclear nickel complex. The luminescent property for complex 1 and magnetic behaviors for complexes 2 and 3 have been investigated.     

Two Isostructural Layered Lanthanide(III) Complexes: Syntheses,Structures, Magnetic and Luminescent Properties

Two N'-(2-hydroxybenzylidene)pyridine N-oxide-carbohydrazide (H₃L)-based coordination complexes with the formula [Ln₂(DMF)₂(OAc)₂(HL)₂]_n (Ln = Dy for 1 and Eu for 2 ) were solvothermally synthesized. Crystal structures, thermal stabilities, magnetic and luminescent properties of the two complexes were fully investigated. Both complexes are isomorphic two-dimensional layers with centrosymmetric {Ln₂} subunits extended by doubly deprotonated HL^2– connectors. Complex 1 with highly anisotropic Dy^III spin exhibits slightly frequency-dependent magnetic relaxations under zero dc field with an effective energy barrier of ca. 6.84 K. Eu^III-based complex 2 displays only one weak fluorescent emission around 532 nm with the absence of characteristic emission of Eu^III ion. These results provide helpful hints of the hydrazide Schiff-functionalized organic ligands on the function modulations of the resulting Ln complexes.