One‐Dimensional Ferromagnetically Coupled Bimetallic Chains Constructed with trans‐[Ru(acac)2(CN)2]−: Syntheses,Structures, Magnetic Properties,and Density Functional Theoretical Study

Four cyano‐bridged 1D bimetallic polymers have been prepared by using the paramagnetic building block trans‐[Ru(acac)₂(CN)₂]^? (Hacac=acetylacetone): {[{Ni(tren)}{Ru(acac)₂(CN)₂}][ClO₄]?CH₃OH}_n ( 1 ) (tren=tris(2‐aminoethyl)amine), {[{Ni(cyclen)}{Ru(acac)₂(CN)₂}][ClO₄]? CH₃OH}_n ( 2 ) (cyclen=1,4,7,10‐tetraazacyclododecane), {[{Fe(salen)}{Ru(acac)₂(CN)₂}]}_n ( 3 ) (salen^2?=N,N′‐bis(salicylidene)‐o‐ethyldiamine dianion) and [{Mn(5,5′‐Me₂salen)}₂{Ru(acac)₂(CN)₂}][Ru(acac)₂(CN)₂]? 2 CH₃OH ( 4 ) (5,5′‐Me₂salen=N,N′‐bis(5,5′‐dimethylsalicylidene)‐o‐ethylenediimine). Compounds 1 and 2 are 1D, zigzagged NiRu chains that exhibit ferromagnetic coupling between Ni^II and Ru^III ions through cyano bridges with J=+1.92 cm^?1, z J′=?1.37 cm^?1, g=2.20 for 1 and J=+0.85 cm^?1, z J′=?0.16 cm^?1, g=2.24 for 2 . Compound 3 has a 1D linear chain structure that exhibits intrachain ferromagnetic coupling (J=+0.62 cm^?1, z J′=?0.09 cm^?1, g=2.08), but antiferromagnetic coupling occurs between FeRu chains, leading to metamagnetic behavior with T_N=2.6 K. In compound 4 , two Mn^III ions are coordinated to trans‐[Ru(acac)₂(CN)₂]^? to form trinuclear Mn₂Ru units, which are linked together by π–π stacking and weak Mn???O* interactions to form a 1D chain. Compound 4 shows slow magnetic relaxation below 3.0 K with ?=0.25, characteristic of superparamagnetic behavior. The Mn^III???Ru^III coupling constant (through cyano bridges) and the Mn^III???Mn^III coupling constant (between the trimers) are +0.87 and +0.24 cm^?1, respectively. Compound 4 is a novel single‐chain magnet built from Mn₂Ru trimers through noncovalent interactions. Density functional theory (DFT) combined with the broken symmetry state method was used to calculate the molecular magnetic orbitals and the magnetic exchange interactions between Ru^III and M (M=Ni^II, Fe^III, and Mn^III) ions. To explain the somewhat unexpected ferromagnetic coupling between low‐spin Ru^III and high‐spin Fe^III and Mn^III ions in compounds 3 and 4 , respectively, it is proposed that apart from the relative symmetries, the relative energies of the magnetic orbitals may also be important in determining the overall magnetic coupling in these bimetallic assemblies.     

A mixed‐valence manganese(III)–manganese(IV) di‐μ‐oxo complex, [(cyclam)MnO]2(ClO4)2(NO3)

The title dinuclear di‐μ‐oxo‐bis­[(1,4,8,11‐tetra­aza­cyclo­tetra­decane‐κ⁴N)­manganese(III,IV)] diperchlorate nitrate complex, [Mn₂O₂(C₁₀H₂₄N₄)₂](ClO₄)₂(NO₃) or [(cyclam)Mn­O]₂(ClO₄)₂(NO₃), was self‐assembled by the reaction of Mn²⁺ with 1,4,8,11‐tetra­aza­cyclo­tetra­decane in aqueous media. The structure of this compound consists of a centrosymmetric binuclear [(cyclam)MnO]³⁺ unit, two perchlorate anions and one nitrate anion. While the low‐temperature electron paramagnetic resonance spectra show a typical 16‐line signal for a di‐μ‐oxo Mn^III/Mn^IV dimer, the magnetic susceptibility studies also confirm a characteristic antiferromagnetic coupling between the electronic spins of the Mn^IV and Mn^III ions.     

A novel one‐dimensional complex: catena‐poly­[[manganese(III)‐di‐μ‐2‐[(2‐hydroxy­ethyl)­imino­methyl]­phenolato‐κ2O1,N:κO2;κO2:κ2O1] chloride]

In the title one‐dimensional complex, {[Mn^III(C₉H₁₀NO₂)₂]Cl}_n, the Schiff base ligand 2‐[(2‐hydroxy­ethyl)­imino­methyl]­phenolate (Hsae⁻) functions as both a bridging and a chelating ligand. The Mn^III ion is six‐coordinated by two N and four O atoms from four different Hsae⁻ ligands, yielding a distorted MnO₄N₂ octahedral environment. Each [Mn^III(Hsae)₂]⁺ cationic unit has the Mn atom on an inversion centre and each [Mn^III(Hsae)₂]⁺ cation lies about another inversion centre. The chain‐like complex is further extended into a three‐dimensional network structure through Cl⋯H—O hydrogen bonds and C—H⋯π contacts involving the Hsae⁻ rings.     

Aquachloro[N,N′‐ethylenebis(salicylideneiminato)]manganese(III)

The title compound, aqua­chloro{2,2′‐[1,2‐ethanediyl­bis­(nitrilo­methyl­idyne)]­diphenolato‐κ⁴O,N,N′,O′}manganese(III),[MnCl(C₁₆H₁₄N₂O₂)(H₂O)], is a neutral manganese(III) complex with a pseudo‐octahedral metal centre. The equatorial plane comprises the four donor atoms of the tetradentate Schiff base ligand [Mn—O 1.886 (4) and 1.893 (4) Å, and Mn—N 1.978 (5) and 1.982 (5) Å], with a water mol­ecule [Mn—O 2.383 (4) Å] and a Cl^? ligand [Mn—Cl 2.4680 (16) Å] completing the coordination sphere. The distorted geometry is highlighted by the marked displacement of the Mn^III ion out of the least‐squares plane of the four Schiff base donor atoms by 0.165 (2) Å. These monomeric Mn^III centres are then linked into a polymeric array via hydrogen bonds between the coordinated water mol­ecule and the phenolic O‐atom donors of an adjacent Mn^III centre [O—H?O 2.789 (5) and 2.881 (5) Å].     

Field‐Induced Slow Magnetic Relaxation in a Mononuclear Manganese(III)–Porphyrin Complex

We report on a novel manganese(III)–porphyrin complex with the formula [Mn^III(TPP)(3,5‐Me₂pyNO)₂]ClO₄?CH₃CN ( 2 ; 3,5‐Me₂pyNO=3,5‐dimethylpyridine N‐oxide, H₂TPP=5,10,15,20‐tetraphenylporphyrin), in which the Mn^III ion is six‐coordinate with two monodentate 3,5‐Me₂pyNO molecules and a tetradentate TPP ligand to build a tetragonally elongated octahedral geometry. The environment in 2 is responsible for the large and negative axial zero‐field splitting (D=?3.8 cm^?1), low rhombicity (E/|D|=0.04) of the high‐spin Mn^III ion, and, ultimately, for the observation of slow magnetic‐relaxation effects (E_a=15.5 cm^?1 at H=1000 G) in this rare example of a manganese‐based single‐ion magnet (SIM). Structural, magnetic, and electronic characterizations were carried out by means of single‐crystal diffraction studies, variable‐temperature direct‐ and alternating‐current measurements and high‐frequency and ‐field EPR spectroscopic analysis followed by quantum‐chemical calculations. Slow magnetic‐relaxation effects were also observed in the already known analogous compound [Mn^III(TPP)Cl] ( 1 ; E_a=10.5 cm^?1 at H=1000 G). The results obtained for 1 and 2 are compared and discussed herein.     

trans‐Bis(cyano‐κC)(1,4,8,11‐tetraazacyclotetradecane‐κ4N)manganese(III) perchlorate,a low‐spin manganese(III) complex

The crystal structure of the low‐spin (S = 1) Mn^III complex [Mn(CN)₂(C₁₀H₂₄N₄)]ClO₄, or trans‐[Mn(CN)₂(cyclam)](ClO₄) (cyclam is the tetradentate amine ligand 1,4,8,11‐tetra­aza­cyclo­tetra­decane), is reported. The structural parameters in the Mn(cyclam) moiety are found to be insensitive to both the spin and the oxidation state of the Mn ion. The difference between high‐ and low‐spin Mn^III complexes is that a pronounced tetragonal elongation of the coordination octahedron occurs in high‐spin complexes and a slight tetragonal compression is seen in low‐spin complexes, as in the title complex.     

Can Anisotropic Exchange Be Reliably Calculated Using Density Functional Methods? A Case Study on Trinuclear MnIII‐MIII‐MnIII (M=Fe,Ru, and Os) Cyanometalate Single‐Molecule Magnets

Density functional studies have been performed on a set of trinuclear single‐molecule magnets (SMMs) of general formula [{Mn₂(5‐Br salen)₂(MeOH)₂}M(CN)₆](NEt₄) (M=Fe^III ( 1 ), Ru^III ( 2 ) and Os^III ( 3 ); 5‐Brsalen=N,N′‐ethylenebis(5‐bromosalicylidene)iminato anion). We have computed the orbital‐dependent exchange interaction for all three complexes for the first time using DFT and complete active space self‐consistent field (CASSCF) methods. DFT calculations yield the anisotropic exchange as J_ξξ=3.5 cm^?1 for 1 ; J_ξξ=12.1 cm^?1, J_ζζ=?6.9 cm^?1 and J_ηη=?14 cm^?1 for 2 ; and J_ξξ=23.7 cm^?1 and J_ζζ=?11.1 cm^?1 for 3 . The computed values are in agreement with the experimental report, and this suggests that the established methodology can be used to compute the anisotropic exchange in larger clusters. Our calculations reiterate the fact that the exchange is described by a three‐axis anisotropic exchange for complexes 2 and 3 as evidenced by the experiments. A stronger exchange coupling as we move down the periodic table from 3d to 5d is reproduced by our calculations, and the origin of this enhancement in the exchange interaction has been probed by using molecular orbital analysis. The electronic origin of different types of exchange observed in this series is found to be related to the energy difference between possible degenerate pairs and the nature of orbital interactions. By computing the exchange interaction, the single‐ion anisotropy of Mn^III and zero‐field splitting of the S=9/2 ground state of complexes 1 – 3 using CASSCF and/or DFT methods, we have attempted to shed light on the issue of anisotropic exchange and the barrier height for the magnetisation reversal in SMMs. Comprehensive magneto–structural correlations have been developed to offer clues on how to further enhance the barrier height in this class of SMMs.     

Syntheses,Structures and Electrochemistry Properties of Two Dicyanamide Manganese(III) Complexes [Mn(5‐Brsalen)(dca)]·CH3OH and [Mn(3‐Meosalphen)(dca)(H2O)]

Two manganese(III)‐dicyanamide compounds, [Mn(5‐Brsalen)(dca)] · CH₃OH ( 1 ) and [Mn(3‐Meosalphen)(dca)(H₂O)] ( 2 ) (dca = dicyanamide anion, [N(CN)₂]^–), were synthesized and characterized by elemental analysis, IR spectroscopy, single‐crystal X‐ray structure analysis, and cyclic voltammetry. The structure of complex 1 is an infinite zigzag chain of hexacoordinate Mn^III ions, in which the adjacent manganese atoms are connected by dca in μ_1,5‐bridging mode. The molecular structure of complex 2 consists of a hexacoordinate Mn^III atom, which generates a slightly distorted octahedral arrangement, and a dimer structure is formed by intermolecular hydrogen bonding interactions. The electrochemical properties of the two complexes were measured by cyclic voltammetry.     

A {Tb2Fe3} Pyramid Single‐Molecule Magnet with Ferromagnetic Tb‐Fe Interaction

The influence of magnetic interactions to the magnetization dynamics was well experimentally studied in a 3d‐4f single‐molecule magnet (SMM) [Tb^III₂Fe^III₃(μ₅‐O)L₂(NO₃)₄Cl] ( 1 , H₄L = N,N,N’,N’‐tetrakis(2‐hydroxyethyl)ethylene diamine) and its diamagnetic‐ ion‐diluted samples. Significant ferromagnetic coupling between Tb^III and Fe^III ions and SMM behavior of 1 were observable, which proved clearly that the magnetic interaction between 3d‐4f spin carriers has also an excessive impact on fine‐tuning the magnetization dynamic behaviors of 3d‐4f complexes.     

Theoretical study of the magnetic exchange coupling behavior substituting Cr(III) with Mo(III) in cyano‐bridged transition metal complexes

Molecular magnetism in a series of cyano‐bridged first and second transition metal complexes has been investigated using density functional theory (DFT) combined with the broken‐symmetry (BS) approach. Several exchange‐correlation (XC) functionals in the ADF package were used to investigate complexes I [?(Me₃tacn)₂(cyclam)NiMo₂(CN)₆]²⁺, II [?(Me₃tacn)₂(cyclam)Ni‐Cr₂(CN)₆]²⁺, III [(Me₃tacn)₆MnMo₆(CN)₁₈]²⁺, and IV [(Me₃tacn)₆MnCr₆(CN)₁₈]²⁺ (Me₃tacn = N,N′,N?‐trimethyl‐1,4,7‐triazacyclononane). For models A (the molded structure of complex I) and B (the modeled structure of complex II), all the XCs given qualitatively reasonable results and predict ferromagnetic coupling character between M (M = Mo^III for A or Cr^III for B) and Ni^II in coincidence with the experimental results (see Tables I and II ). The calculated using Operdew, OPBE, O3LYP, and B3LYP functionals and experimental J values show that substituting Cr^III with Mo^III will enhance the ferromagnetic exchange coupling interactions. But VWN, PW91, PBE, VSXC, and tau‐HCTH functionals have no way to differentiate the relative strength of the intramolecular magnetic exchange coupling interactions of A and B correctly. For models C (the modeled structure of complex III) and D (the modeled structure of complex IV), all the XCs in ADF and B3LYP in Gaussian 03 with several basis sets show that substituting Cr^III with Mo^III will enhance the antiferromagnetic exchange coupling interactions. From the above calculations, the substitution of Cr^III by Mo^III will enhance the magnetic coupling interactions, whether the magnetic coupling interactions are ferro‐ or antiferromagnetic. Moreover, Kahn's model was applied to investigate the above facts. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

Mechanistic disparity in the electron transfer reactions of thiosulfate with di‐μ‐oxo‐bis(1,4,8,11‐tetraazacyclotetradecane)‐dimanganese(III,IV) and di‐μ‐oxo‐bis(1,4,7,10‐tetraazacyclododecane)‐dimanganese(III,IV) complexes

A comparative kinetic study of the reactions of two mixed valence manganese(III,IV) complexes of macrocyclic ligands, [L¹Mn^IV(O)₂Mn^IIIL¹], 1 (L¹ = 1,4,8,11‐tetraazacyclotetradecane) and [L²Mn^IV(O)₂Mn^IIIL²], 2 (L² = 1,4,7,10‐tetraazacyclododecane) with thiosulfate has been carried out by spectrophotometry in aqueous buffer at 30°C. Reaction between complex 1 and thiosulfate follows a first‐order rate saturation kinetics. The pH dependency and kinetic evidences suggest the participation of two complex species of Mn^III(μ‐O)₂Mn^IV under the experimental conditions. Detailed kinetic study shows that reduction of 2 proceeds through an autocatalytic path where the intermediate (Mn^III)₂ species has been assumed to catalyze the reaction. The difference in the reaction mechanisms is ascribed to the difference in stability of the intermediate complex species, the evidence for which comes from the electrochemical behavior of the complexes and time dependent EPR spectroscopic measurements during the reduction of 2 . © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 119–128, 2004     

Mimicking Class I b Mn2‐Ribonucleotide Reductase: A MnII2 Complex and Its Reaction with Superoxide

A fascinating discovery in the chemistry of ribonucleotide reductases (RNRs) has been the identification of a dimanganese (Mn₂) active site in class I b RNRs that requires superoxide anion (O₂^.?), rather than dioxygen (O₂), to access a high‐valent Mn₂ oxidant. Complex 1 ([Mn₂(O₂CCH₃)(N‐Et‐HPTB)](ClO₄)₂, N‐Et‐HPTB=N,N,N′,N′‐tetrakis(2‐(1‐ethylbenzimidazolyl))‐2‐hydroxy‐1,3‐diaminopropane) was synthesised in high yield (90 %). 1 was reacted with O₂^.? at ?40 °C resulting in the formation of a metastable species ( 2 ). 2 displayed electronic absorption features (λ_max=460, 610 nm) typical of a Mn‐peroxide species and a 29‐line EPR signal typical of a Mn^IIMn^III entity. Mn K‐edge X‐ray absorption near‐edge spectroscopy (XANES) suggested a formal oxidation state change of Mn^II₂ in 1 to Mn^IIMn^III for 2 . Electrospray ionisation mass spectrometry (ESI‐MS) suggested 2 to be a Mn^IIMn^III‐peroxide complex. 2 was capable of oxidizing ferrocene and weak O?H bonds upon activation with proton donors. Our findings provide support for the postulated mechanism of O₂^.? activation at class I b Mn₂ RNRs.     

Syntheses,Structures and Magnetic Properties of Two Mixed‐Valent Disc‐like Hepta‐nuclear Compounds of [FeIIFeIII6(tea)6](ClO4)2 and [MnII3MnIII4(nmdea)6(N3)6]·CH3OH (tea = N(CH2CH2O)33−, nmdea = CH3N(CH2CH2O)22−)

Two mixed‐valent disc‐like hepta‐nuclear compounds of [Fe^IIFe^III₆(tea)₆](ClO₄)₂ ( 1Fe , tea = N(CH₂CH₂O)₃^3?) and [Mn^II₃Mn^III₄(nmdea)₆(N₃)₆]·CH₃OH ( 2Mn , nmdea = CH₃N(CH₂CH₂O)₂^2?) have been synthesized by the reaction of Fe(ClO₄)₂·6H₂O with triethanolamine (H₃tea) for the former and reaction of Mn(ClO₄)₂·6H₂O with diethanolamine (H₂nmdea) and NaN₃ for the later, respectively. 1Fe has the cationic cluster with a planar [Fe^IIFe^III₆] core consisting of one central Fe^II and six rim Fe^III atoms in hexagonal arrangement. The Fe ions are linked by the oxo‐bridges from the alcohol arms in the manner of edge‐sharing of their coordination octahedra. 2Mn is a neutral cluster with a [Mn^II₃Mn^III₄] core possessing one central Mn^II atom surrounded by six rim Mn ions, two Mn^II and four Mn^III. The structure is similar to 1Fe but involves six terminal azido ligands, each coordinate one rim Mn ion. 1Fe showed dominant antiferromagnetic interaction within the cluster and long‐range ordering at 2.7 K. The cluster probably has a ground state of low spin of S = 5/2 or 4/2. The long‐range ordering is weak ferromagnetic, showing small hysteresis with a remnant magnetization of 0.3 Nβ and a coercive field of 40 Oe. Moreover, the isofield of lines 1Fe are far from superposition, indicating the presence of significant zero–field splitting. Ferromagnetic interactions are dominant in 2Mn . An intermediate spin ground state 25/2 is observed at low field. In high field of 50 kOe, the energetically lowest state is given by the m_s = 31/2 component of the S = 31/2 multiplet due to the Zeeman effect. Despite of the large ground state, no single‐molecule magnet behavior was found above 2 K.     

A New Mixed‐Valence Tetranuclear Manganese [MnII2MnIII2] Cluster

A new tetranuclear manganese complex [Mn₂^IIMn₂^III(bhmcpH)₂(hmp)₄Cl₂(MeOH)₂] ( 1 ) [bhmcpH₃ = 2, 6‐bis(hydroxymethyl)‐4‐chlorophenol, hmpH = 2‐(hydroxymethyl)pyridine] was synthesized and characterized. X‐ray diffraction analyses reveal that complex 1 crystallizes in the monoclinic space group P2₁/c. It has a mixed‐valence tetranuclear dicubane unit, which comprises two Mn^II and two Mn^III ions. The temperature dependence of the magnetic susceptibilities of 1 indicates ferromagnetic interactions between the manganese ions.     

Bis[μ3‐1,8‐bis(triisopropylsilylamido)naphthalene]bis(tetrahydrofuran)di‐μ3‐oxido‐dimanganese(III)disodium

The solid‐state structure of the title compound, [Na₂Mn₂(C₃₂H₅₆N₂OSi₂)₂O₂] or [1,8‐C₁₀H₆(NSiⁱPr₃)₂Mn(μ₃‐O)Na(THF)]₂, which lies across a crystallographic twofold axis, exhibits a central [Mn₂O₂Na₂]⁴⁺ core, with two oxide groups, each triply bridging between the two Mn^III ions and an Na⁺ ion. Additional coordination is provided to each Mn^III centre by a 1,8‐C₁₀H₆(NSiⁱPr₃)₂ [1,8‐bis(triisopropylsilylamido)naphthalene] ligand and to the Na⁺ centres by a tetrahydrofuran molecule. The presence of an additional Na...H—C agostic interaction potentially contributes to the distortion around the bridging oxide group.     

Mononuclear manganese(II) and manganese(III) complexes of N<Subscript>2</Subscript>O donors involving amine and phenolate ligands: absorption spectra,electrochemistry and crystal structure of [Mn(L<Subscript>3</Subscript>)<Subscript>2</Subscript>](ClO<Subscript>4</Subscript>)

A number of mononuclear manganese(II) and manganese(III) complexes have been synthesized from tridentate N₂O aminophenol ligands (HL₁–HL₅) formed by reduction of corresponding Schiff bases with NaBH₄. Three types of tridentate N₂O aminophenols have been prepared by reducing with NaBH₄which are (a) Schiff bases obtained by bromo salicylaldehyde reaction with N,N-dimethyl/N,N-diethyl ethylene diamine (HL₁, HL₂), (b) Schiff bases obtained by condensing salicylaldehyde/bromo salicylaldehyde and picolyl amine (HL₃, HL₄), (c) pyridine-2-aldehyde and 2-aminophenol (HL₅). All the manganese complexes have been prepared by direct addition of manganese perchlorate to the corresponding ligands and were characterized by the combination of i.r., u.v.–vis spectroscopy, magnetic moments and electrochemical studies. The u.v.–vis spectra of all of the manganese(III) complexes show two weak d–d transitions in the 630–520 nm region, which support a distorted octahedral geometry. The electron transfer properties of all of the manganese(III) complexes (1–4 and 6) exhibit mostly similar characteristics consisting two redox couples corresponding to the Mn^III → Mn^II reductions and Mn^III → Mn^IV oxidations. The electronic effect on the potential has also been studied by changing different substituents in the ligands. In all cases, an electron-donating group stabilizes the higher oxidation state and electron withdrawing group prefers the lower oxidation state. The cyclic voltammogram of [Mn^II(L₅)₂] shows an irreversible oxidation Mn^II → Mn^III at −0.88 V, followed by another quasi-reversible oxidation Mn^III → Mn^IV at +0.48 V. The manganese(III) complex (3) [Mn(L₃)₂]ClO₄has been characterized by X-ray crystallography.     

A mixed‐valence diacetate‐bridged MnII–MnIII complex incorporating a bridging phenolate ligand

The synthesis and characterization of a new unsymmetrical dinucleating N,O‐donor ligand, 2‐[N,N‐bis­(2‐pyridyl­methyl)­amino­methyl]‐6‐[N‐(3,5‐di‐tert‐butyl‐2‐oxidobenzyl)‐N‐(2‐pyridyl­amino)­aminomethyl]‐4‐methyl­phenol (H₂Ldtb), as well as the X‐ray crystal structure of its corresponding mixed‐valence diacetate‐bridged manganese complex, di‐μ‐acetato‐μ‐{2‐[N,N‐bis­(2‐pyridylmethyl)amino­methyl]‐6‐[N‐(3,5‐di‐tert‐butyl‐2‐oxidobenzyl)‐N‐(2‐pyridyl­amino)­aminomethyl]‐4‐methylphenolato}dimanganese(II,III) tetra­phenyl­borate, [Mn^IIMn^III(C₄₂H₄₉N₅O₂)(C₂H₃O₂)₂](C₂₄H₂₀B), are reported. The complex may be regarded as an inter­esting structural model for the mixed‐valence Mn^II–Mn^III state of manganese catalase.     

A pentanuclear bimetallic complex of manganese(II) and aluminium(III) ions: tetra‐μ2‐iodido‐iodidobis(μ3‐2‐methoxyethanolato)bis(μ2‐2‐methoxyethanolato)dimethyl(tetrahydrofuran‐κO)aluminium(III)tetramanganese(II)

The molecule of the title compound, [Mn₄Al(CH₃)₂(C₃H₇O₂)₄I₅(C₄H₈O)], contains one Al^III and four Mn^II ions. Two Mn atoms are five‐coordinate in the form of a trigonal bipyramid or a square pyramid. The two other Mn atoms are six‐coordinate with an octahedral geometry. The fourcoordinate Al atom is linked to the manganese core by μ‐O_alkoxo bridges, forming an almost planar five‐membered ring.     

A cyanide‐bridged FeIII–MnII heterobimetallic one‐dimensional coordination polymer: synthesis,crystal structure,experimental and theoretical magnetism investigation

A new cyanide‐bridged Fe^III–Mn^II heterobimetallic coordination polymer (CP), namely catena‐poly[[[N,N′‐(1,2‐phenylene)bis(pyridine‐2‐carboxamidato)‐κ⁴N,N′,N′′,N′′′]iron(III)]‐μ‐cyanido‐κ²C:N‐[bis(4,4′‐bipyridine‐κN)bis(methanol‐κO)manganese(II)]‐μ‐cyanido‐κ²N:C], {[FeMn(C₁₈H₁₂N₄O₂)(CN)₂(C₁₀H₈N₂)₂(CH₃OH)₂]ClO₄}_n, ( 1 ), was prepared by the self‐assembly of the trans‐dicyanidoiron(III)‐containing building block [Fe(bpb)(CN)₂]^? [bpb^2? = N,N′‐(1,2‐phenylene)bis(pyridine‐2‐carboxamidate)], [Mn(ClO₄)₂]·6H₂O and 4,4′‐bipyridine, and was structurally characterized by elemental analysis, IR spectroscopy, single‐crystal X‐ray crystallography and powder X‐ray diffraction (PXRD). Single‐crystal X‐ray diffraction analysis shows that CP 1 possesses a cationic linear chain structure consisting of alternating cyanide‐bridged Fe–Mn units, with free perchlorate as the charge‐balancing anion, which can be further extended into a two‐dimensional supramolecular sheet structure via inter‐chain π–π interactions between the 4,4′‐bipyridine ligands. Within the chain, each Mn^II ion is six‐coordinated by an N₆ unit and is involved in a slightly distorted octahedral coordination geometry. Investigation of the magnetic properties of 1 reveals an antiferromagnetic coupling between the cyanide‐bridged Fe^III and Mn^II ions. A best fit of the magnetic susceptibility based on the one‐dimensional alternating chain model leads to the magnetic coupling constants J₁ = ?1.35 and J₂ = ?1.05 cm^?1, and the antiferromagnetic coupling was further confirmed by spin Hamiltonian‐based density functional theoretical (DFT) calculations.     

trans‐Diaquabis(1H‐imidazole‐4,5‐di­carboxyl­ate‐κ2N3,O4)­manganese(II)

In the title compound, [Mn(C₅H₃N₂O₄)₂(H₂O)₂], the Mn^II atom lies on an inversion centre, is trans‐coordinated by two N,O‐bidentate 1H‐imidazole‐4,5‐di­carboxyl­ate monoanionic ligands [Mn—O = 2.202 (3) Å and Mn—N = 2.201 (4) Å] and two water mol­ecules [Mn—O = 2.197 (4) Å], and exhibits a distorted octahedral geometry, with adjacent cis angles of 76.45 (13), 86.09 (13) and 89.20 (13)°. The complete solid‐state structure can be described as a three‐dimensional supramol­ecular framework, stabilized by extensive hydrogen‐bonding interactions involving the coordinated water mol­ecules, the carboxy O atoms and the protonated imidazole N atoms of the imidazole‐4,5‐di­carboxyl­ate ligands.