Mn-N Bond Research Articles

Structural Characterization of a Series of N5-Ligated MnIV -Oxo Species.

Analysis of extended X-ray absorption fine structure (EXAFS) data for the MnIV -oxo complexes [MnIV (O)(DMM N4py)]2+ , [MnIV (O)(2pyN2B)]2+ , and [MnIV (O)(2pyN2Q)]2+ (DMM N4py=N,N-bis(4-methoxy-3,5-dimethyl-2-pyridylmethyl)-N-bis(2-pyridyl)methylamine; 2pyN2B=(N-bis(1-methyl-2-benzimidazolyl)methyl-N-(bis-2-pyridylmethyl)amine, and 2pyN2Q=N,N-bis(2-pyridyl)-N,N-bis(2-quinolylmethyl)methanamine) afforded Mn=O and Mn-N bond lengths. The Mn=O distances for [MnIV (O)(DMM N4py)]2+ and [MnIV (O)(2pyN2B)]2+ are 1.72 and 1.70 Å, respectively. In contrast, the Mn=O distance for [MnIV (O)(2pyN2Q)]2+ was significantly longer (1.76 Å). We attribute this long distance to sample heterogeneity, which is reasonable given the reduced stability of [MnIV (O)(2pyN2Q)]2+ . The Mn=O distances for [MnIV (O)(DMM N4py)]2+ and [MnIV (O)(2pyN2B)]2+ could only be well-reproduced using DFT-derived models that included strong hydrogen-bonds between second-sphere solvent 2,2,2-trifluoroethanol molecules and the oxo ligand. These results suggest an important role for the 2,2,2-trifluoroethanol solvent in stabilizing MnIV -oxo adducts. The DFT methods were extended to investigate the structure of the putative [MnIV (O)(N4py)]2+ ⋅(HOTf)2 adduct. These computations suggest that a MnIV -hydroxo species is most consistent with the available experimental data.

Effect of Appended S-Block Metal Ion Crown Ethers on Redox Properties and Catalytic Activity of Mn-Nitride Schiff Base Complexes: Methane Activation.

Using density functional theory (DFT), the effects of appended s-block metal ion crown ethers upon the redox properties of the following nitridomanganese(V) salen complexes were investigated: [(salen)MnV(N)(Mn+-crown ether)]n+ (salen = N,N'-bis(salicydene)ethylenediamine; M = Na+, K+, Ba2+, and Sr2+ for 1Na, 1K, 1Ba, and 1Sr, respectively; A = complex without Mn+-crown ether and B = without Mn+). NBO analysis of the MnN bond orders, optimized bond lengths, and stretching frequencies changes upon oxidation for all species show that for A, B, and 1Na MnN has more nitridyl character while a nitride form is more significant for 1K, 1Ba, and 1Sr. The results reveal that ΔGrxn(e-) and thus E1/2 are quite sensitive to the point charge (q) of the s-block metal ions (1 for K+/Na+ and 2 for Ba2+/Sr2+). Computations suggest that the degree of delocalization of the HOMO electrons on the supporting ligand is modified by the chelated s-block metal ion. Methane activation by A•+, 1K•+, and 1Ba•+ complexes proceeds via a hydrogen atom transfer (HAT) pathway with reasonable barriers for all complexes with ∼4 kcal/mol difference in energy. The molecular electrostatic potential (MEP) maps indicate a shift in redox potential imposed by the nonredox active cations by altering the electrostatic potential of the complexes. Computations show that the complexes with higher point charge of the incorporated metal ions result in higher N-H bond BDFEs. Changes in predicted properties as a function of continuum solvent dielectric constant suggest that the primary effect of the appended s-block ion is via "through space" interactions.

The First Conducting Spin‐Crossover Compound Combining a MnIII Cation Complex with Electroactive TCNQ Demonstrating an Abrupt Spin Transition with a Hysteresis of 50 K

We present herein the synthesis, crystal structure, and electric and magnetic properties of the spin-crossover salt [Mn(5-Cl-sal-N-1,5,8,12)]TCNQ1.5 ⋅2 CH3 CN (I), where 5-Cl-sal-N-1,5,8,12=N,N'-bis(3-(2-oxy-5-chlorobenzylideneamino)propyl)-ethylenediamine, containing distinct conductive and magnetic blocks along with acetonitrile solvent molecules. The MnIII complex with a Schiff-base ligand, [Mn(5-Cl-sal-N-1,5,8,12)]+ , acts as the magnetic unit, and the π-electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ- ) is the conducting unit. The title compound (I) exhibits semiconducting behavior with room temperature conductivity σRT ≈1×10-4 ohm-1 cm-1 and activation energy Δ ≈0.20 eV. In the temperature range 73-123 K, it experiences a hysteretic phase transition accompanied by a crossover between the low-spin S=1 and high-spin S=2 states of MnIII and changes in bond lengths within the MnN4 O2 octahedra. The pronounced shrinkage of the basal Mn-N bonds in I at the spin crossover suggests that the d orbital is occupied/deoccupied in this transition. Interestingly, the bromo isomorphic counterpart [Mn(5-Br-sal-N-1,5,8,12)]TCNQ1.5 ⋅2 CH3 CN (II) of the title compound evidences no spin-crossover phenomena and remains in the high-spin state in the temperature range 2-300 K. Comparison of the chloro and bromo compounds allows the thermal and spin-crossover contributions to the overall variation in bond lengths to be distinguished. The difference in magnetic behavior of these two salts has been ascribed to intermolecular supramolecular effects on the spin transition. Discrete hydrogen bonding exists between cations and cations and anions in both compounds. However, the hydrogen bonding in the crystals of II is much stronger than in I. The relatively close packing arrangement of the [Mn(5-Br-sal-N-1,5,8,12)]+ cations probably precludes their spin transformation.

Sponge Effect Boosting Oxygen Reduction Reaction at the Interfaces between Mullite SmMn2O5 and Nitrogen-Doped Reduced Graphene Oxide.

Exploring the effect of interfacial structural properties on catalytic performance of hybrid materials is essential in rationally designing novel electrocatalysts with high stability and activity. Here, in situ growth of mullite SmMn2O5 on nitrogen-doped reduced graphene oxide (SMO@NrGO) is achieved for highly efficient oxygen reduction reaction (ORR). Combining X-ray photoelectron spectroscopy and density functional theory calculations, interfacial chemical interactions between Mn and substrates are verified. Interestingly, as revealed by charge density difference, the interfacial Mn-N(C) bonds display a sponge effect to store and compensate electrons to boost the ORR process. In addition, bidentate adsorption of oxygen intermediates instead of monodentate ones is observed in hybrid materials, which facilitates the interactions between intermediates and active sites. Experimentally, the hybrid catalyst SMO@NrGO exhibits a half-wave potential as high as 0.84 V, being comparable to benchmark Pt/C and higher than that of the pure SMO (0.68 V). The Zn-air battery assembled with SMO@NrGO shows a high discharge peak power density of 244 mW cm-2 and superior cycling stability against noble metals.

Electronic structures and crystal field splitting of antiperovskite XNMn3 (X = 3d and 4d elements)

Antiperovskites have diverse novel physical properties and potential applications in fields of superconducting techniques, magneto-electronic devices, etc. Nevertheless, their fundamental electronic structures, such as ground state magnetic configurations and crystal field splitting, are still not yet fully understood. We thus utilize first principles calculations combining on-site Coulomb interaction of the Mn-3d orbitals to investigate the electronic and magnetic properties of the XNMn3 (X=Ni, Cu, Zn, Ga, As, Rh, Pd, Ag, In, Sn, Sb). Our results show that the Mn atoms prefer to align antiferromagnetic configuration in the ground state. Two nonequivalent Mn atoms (NEMAS) are identified in Mn6N octahedral unit. The Mn-3d orbitals with longer Mn-N bond length in the octahedron split into one doublet and three singlets, and the 3d orbitals of other Mn atoms with shorter Mn-N bond length split in five singlets, i.e. the degeneracy is completely relieved. These findings certainly offer an insight into clarifying the magnetic and electronic properties of these antipervoskites.

Synthesis, experimental and theoretical characterization of a Mn(II) complex of N,N′-dipyridoxyl(1,2-diaminobenzene)

Herein, hopping to biological and catalytic applications, synthesis of a Mn(II) complex of the N,N′-dipyridoxyl(1,2-diaminobenzene) [H2L] Schiff-base has been reported. The Mn complex was characterized experimentally and theoretically. The optimized geometry and vibrational frequencies of the complex were computed by using the density functional theory (DFT) methods. In the optimized geometry of the octahedral complex, the dianionic L2− acts as a tetradentate ligand. Four coordination positions of the square plane have been occupied with two azomethine nitrogens and two phenolic oxygens of the L2− ligand. Two coordinated methanol ligands are perpendicular to the square plane. Also, properties of the MnN and MnO bonds were explored investigated using the Atoms in molecules (AIM) analysis.

Combined Mössbauer Spectral and Density Functional Study of an Eight-Coordinate Iron(II) Complex.

The iron-57 Mössbauer spectra of the eight-coordinate complex, [Fe(L(N4))2](BF4)2, where L(N4) is the tetradentate N(1)(E),N(2)(E)-bis[(1-methyl-1H-imidazol-2-yl)methylene]-1,2-benzenediimine ligand, have been measured between 4.2 and 295 K and fit with a quadrupole doublet. The fit at 4.2 K yields an isomer shift, δ(Fe), of 1.260(1) mm/s and a quadrupole splitting, ΔE(Q), of 3.854(2) mm/s, values that are typical of a high-spin iron(II) complex. The temperature dependence of the isomer shift yields a Mössbauer temperature, Θ(M), of 319(27) K and the temperature dependence of the logarithm of the Mössbauer spectral absorption area yields a Debye temperature, Θ(D), of 131(6) K, values that are indicative of high-spin iron(II). Nonrelativistic single point density functional calculations with the B3LYP functional, the full 6-311++G(d,p) basis set, and the known X-ray structures for [Mn(L(N4))2](2+), [Mn(L(N4))2](ClO4)2, 1, [Fe(L(N4))2](2+), and [Fe(L(N4))2](BF4)2, 2, yield small electric field gradients for the manganese(II) complexes and electric field gradients and s-electron densities at the iron-57 nuclide that are in good to excellent agreement with the Mössbauer spectral parameters. The structure of 2 with a distorted square-antiprism C1 iron(II) coordination symmetry exhibits four different Fe-N(imid) bonds to the imidazole nitrogens with an average bond distance of 2.253(2) Å and four different Fe-N(imine) bonds to the benzenediimine nitrogens, with an average bond distance of 2.432(2) Å; this large difference yields the large observed ΔE(Q). An optimization of the [Fe(L(N4))2](2+) structure leads to a highly symmetric eight-coordination environment with S4 symmetry and four equivalent Fe-N(imid) bond distances of 2.301(2) Å and four equivalent Fe-N(imine) bond distances of 2.487(2) Å. In contrast, an optimization of the [Mn(LN4)2](2+) structure leads to an eight-coordination manganese(II) environment with D(2d) symmetry and four equivalent Mn-N(imid) bond distances of 2.350(3) Å and four equivalent Mn-N(imine) bond distances of 2.565(3) Å.

Complexes of Mn(II) with imidazole and 2-thiophene acetic acid ligands

The reactions of 2-thiophene acetic acid and imidazole with manganese (II) chloride resulted in mononuclear [Mn(C6H5O2S)2(C3H4N2)6] (1), or binuclear [Mn2(C6H5O2S)4(C3H4N2)4] (2) and [Mn2(C6H5O2S)4(C3H4N2)4(H2O)] (3) complexes. In the complex (1), the Mn ion is octahedral coordinated by six nitrogen atoms from six imidazole rings and the Mn-O bond lengths are in the range 2.261(4) to 2.275(6) Å. The crystal packing is stabilized by weak C-H...O and N-H...O hydrogen bonds. In the structure of (2), the asymmetric unit is formed from an Mn ion bonded to two N atoms from two imidazole ligands and to three O atoms from three different thiophene acetic acid ligands. Two of these ligands are deprotonated and bridge by the same oxygen atoms between the second manganese ion giving rise to an binuclear complex. In this complex, each Mn cation is located in a slightly distorted square-planar environment and the Mn-N bond lengths are in the range 1,960(3) to 1.976(2) Å. The Mn-O bonds lengths in the square base of the two pyramids are in the range 1.956(5) to 2.000(1) Å. The Mn-O axial bond distance is quite longer than the Mn-O equatorial bond distances and is 2.458(2)Å [1,2]. The crystal packing is stabilized by weak C-H...O and N-H...O hydrogen bonds forming connected layers parallel to (001) planes. When an oxygen of one molecule of water bridges the two metal centers in the complex (2), the environment of the two Mn becomes octahedral and thus we obtain the complex (3). In this latter complex, the Mn-N bonds are in the range 2.192(4) to 2.245(4). All Mn-O bonds are between 2.148(6) and 2.232(7)Å. All structures are disordered in all thiophenyl rings occupy alternatively two positions related to one another by an 180o rotation about the C–C sigma bond [3]. The sulfur and one carbon atom of the ring occupy the same position. The complexes were structurally characterized by single crystal X-ray diffraction analyses, infrared spectroscopy (IR), elemental analyses and thermogravimetric analyses (TGA). Cristal data: (1): MnC30H34N12O4S2 in C2/c, a=11.3492(6), b=13.9186(7), c=22.2101(13), beta= 94.963(4) (2): Mn2C36H36N8O8S4 in P21/n, a=15.996(2), b=10.274(13), c=26.141(3), beta=97.715(9) (3): Mn2C24H38N8O9S4 in P21/n, a=26.206(2), b=8.5421(8), c=19.0694(17), beta= 92.229(4)

First principles and experimental study of NH3 adsorptions on MnOx surface

The oxidative abstraction of hydrogen from adsorbed ammonia is the first step in selective catalytic reduction (SCR) and NH3 adsorptions on the MnOx surfaces played a significant role in the mechanism of SCR with NH3. NH3 adsorptions on the Mn2O3 (222), Mn3O4 (211) and MnO2 (110) surfaces were investigated by the density functional theory (DFT) method. With more negative adsorption energy values, the Mn2O3 (222) and Mn3O4 (211) surfaces tended to be the favorable adsorption sites for NH3 molecule. In addition, the shorter MnN bonds indicated that NH3 adsorptions took place easily on Mn2O3 (222) and Mn3O4 (211) surfaces. According to the ammonia temperature programmed desorption (NH3-TPD) performance, Mn2O3 and Mn3O4 showed significantly higher amount of desorbed NH3, which was in good agreement with the DFT study. Meanwhile, the NH3-SCR performances of Mn2O3 and Mn3O4 for NO conversion below 433K show higher performance than that of MnO2.

Cyanide-Bridged WVMnIII Bimetallic Chains Composed of a Blocked W Hexacyanide Precursor: Geometry-Related Magnetic Couplings and Magnetostructural Correlation

Five one-dimensional bimetallic W(V)Mn(III) complexes 1-5, consisting of [W(CN)6(bpy)](-) anions and [Mn(Schiff base)](+) cations, were prepared. The central coordination geometry around each W atom is determined as a distorted dodecahedron (DD) for 1 and 2, and a distorted square antiprism (SAPR) for 3-5. Magnetic analyses demonstrate that compounds 1, 4, and 5 exhibit antiferromagnetic interactions between magnetic centers, which are different from the ferromagnetic couplings in 2 and 3. For the distorted DD geometry, the Mn-N(ax) (ax = axial) bond length increases when moving from 1 to 2, with the Mn-N(ax)-C(ax) angle remaining constant. The elongation of the bond length is responsible for the reduction in orbital overlap and consequent ferromagnetic coupling in 2. In comparison, for 3-5 with the distorted SAPR geometry, given that the Mn-N(ax) bond lengths are similar across all the samples, the increase in the Mn-N(ax)-C(ax) angles accounts for the enhanced magnetic strength. Notably, a correlation between structure and magnetic exchange coupling is established for the first time in W(V)Mn(III) bimetallic systems based on the [W(CN)6(bpy)](-) precursor.

Magnetic configuration, electronic structure, and stability of the low-index surfaces ofη-Mn3N2: A first-principles study

The low-index (001), (010), and (110) surfaces of $\ensuremath{\eta}$-Mn${}_{3}$N${}_{2}$ are investigated using the ab initio generalized gradient (GGA) density functional method. For the bulk crystal, the GGA approach is found to predict correctly its electronic structure and the antiferromagnetic ordering along the [001] direction, with Mn magnetic moments close to 3${\ensuremath{\mu}}_{B}$. The more stable surfaces are the (001) terminated in a MnN plane and the (010), both observed experimentally in $\ensuremath{\eta}$-Mn${}_{3}$N${}_{2}$ thin films grown on MgO (001) crystals. While in the (001) the surface plane consists of Mn atoms ferromagnetically coupled through N, in the (010) surface rows of Mn antiferromagnetically aligned alternate along the [001] direction. Furthermore, our results suggest that, due to its relatively small surface energy, the (110) surface with a singular one-dimensional ribbonlike 8.46 \AA{} width ferromagnetic structure could also be stabilized. Despite their differences, the magnetic configuration of all the surfaces is dictated by the cleavage of the layerwise antiferromagnetic structure of bulk Mn${}_{3}$N${}_{2}$. The broken symmetry of the surface induces atomic corrugations, which however do not alter drastically either the spin configuration or the electronic structure. Mn-N bond states tend to be close to the bottom of the valence bands, and although an enhancement of the surface magnetic moments are obtained, they remain close to the bulk values. All the surfaces are metallic as bulk $\ensuremath{\eta}$-Mn${}_{3}$N${}_{2}$ crystals.

Environmental Influence on the Single-Molecule Magnet Behavior of [MnIII6CrIII]3+: Molecular Symmetry versus Solid-State Effects

The structural, spectroscopic, and magnetic properties of a series of [Mn(III)(6)Cr(III)](3+) (= [{(talen(t-Bu(2)))Mn(III)(3)}(2){Cr(III)(CN)(6)}](3+)) compounds have been investigated by single-crystal X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and electronic absorption spectroscopy, elemental analysis, electro spray ionization-mass spectrometry (ESI-MS) and matrix-assisted laser desorption ionization-mass spectrometry (MALDI-MS), cyclic voltammetry, AC and DC magnetic measurements, as well as theoretical analysis. The crystal structures obtained with [Cr(III)(CN)(6)](3-) as a counterion exhibit (quasi-)one-dimensional (1D) chains formed by hydrogen-bonded (1) or covalently linked (2) trications and trianions. The rod-shaped anion lactate enforces a rod packing of the [Mn(III)(6)Cr(III)](3+) complexes in the highly symmetric space group R3[overline] (3) with a collinear arrangement of the molecular S(6) axes. Incorporation of the spherical anion BPh(4)(-) leads to less-symmetric crystal structures (4-6) with noncollinear orientations of the [Mn(III)(6)Cr(III)](3+) complexes, as evidenced by the angle between the approximate molecular C(3) axes taking no specific values in the range of 2°-69°. AC magnetic measurements on freshly isolated crystals (1a and 3a-6a), air-dried crystals (3b-6b), and vacuum-dried powder samples (3c-6c) indicate single-molecule magnet (SMM) behavior for all samples with U(eff) values up to 28 K. The DC magnetic data are analyzed by a full-matrix diagonalization of the appropriate spin-Hamiltonian including isotropic exchange, zero-field splitting, and Zeeman interaction, taking into account the relative orientation of the D-tensors. Simulations for 3a-6a and 3c-6c indicate a weak antiferromagnetic exchange between the Mn(III) ions in the trinuclear subunits (J(Mn-Mn) = -0.70 to -0.85 cm(-1), Ĥ(ex) = -2∑(i<j )J(ij)Ŝ(i)·Ŝ(j)) that is overcome by the stronger antiferromagnetic interaction via the Cr-C≡N-Mn pathway (J(Cr-Mn) = -3.00 to -5.00 cm(-1)), leading to an overall ferrimagnetic coupling scheme with an S(t) = (21)/(2) spin ground state. The differences in U(eff), J(Mn-Mn), and J(Cr-Mn) for the investigated samples are rationalized in terms of subtle variations in the molecular and crystal structures. In particular, a magnetostructural correlation between the Mn-N(C≡N) bond length and the J(Cr-Mn) exchange coupling is inferred from the magnetic measurements and corroborated by DFT calculations. The results of this detailed study on [Mn(III)(6)Cr(III)](3+) allow the formulation of some key recipes for a rational improvement of the SMM behavior.

Cis-Aquabromidobis(di-2-pyridylamine-κ2N,N′)manganese(II) bromide

In the title compound, [MnBr(C10H9N3)2(H2O)]Br, the MnII ion is six-coordinated in a considerably distorted cis-N4BrO octa­hedral environment defined by four N atoms of two chelating di-2-pyridyl­amine (dpa) ligands, one Br− anion and one O atom of a water ligand. As a result of the different trans effects of Br, N and O atoms, the Mn—N bond trans to the Br atom is slightly longer than the Mn—N bond trans to the N or O atoms. In the crystal, the dpa ligands are not planar, the dihedral angles between the two pyridine rings being 29.2 (4) and 28.2 (3)°. The complex cations and the Br− anions are linked by inter­molecular O—H⋯Br and N—H⋯Br hydrogen bonds. Inter­molecular π–π inter­actions are present between the pyridine rings, with a centroid–centroid distance of 3.793 (4) Å.

Cis-Aquabis(di-2-pyridylamine-κ2N,N′)iodidomanganese(II) iodide

The asymmetric unit of the title compound, [MnI(C10H9N3)2(H2O)]I, contains a cationic MnII complex and an I− anion. In the complex, the MnII ion is six-coordinated in a considerably distorted cis-N4IO octa­hedral environment defined by four N atoms of the two chelating di-2-pyridyl­amine (dpa) ligands, one I− anion and one O atom of a water ligand. As a result of the different trans effects of the I, N and O atoms, the Mn—N bond trans to the I atom is slightly longer than the Mn—N bond trans to the N or O atoms. The dpa ligands are not planar, with dihedral angles between the two pyridine rings of 26.2 (4) and 26.5 (4)°. The complex cations are stacked in columns along the a axis and are linked to the anions by inter­molecular O—H⋯I and N—H⋯I hydrogen bonds.

A second monoclinic polymorph of bis(2,2′-bipyridine-κ2N,N′)diiodidomanganese(II)

The MnII ion in the title complex, [MnI2(C10H8N2)2], is six-coordinated in a distorted cis-N4I2Mn octa­hedral environment by four N atoms of the two chelating 2,2′-bipyridine ligands and two iodide anions. As a result of the different trans effects of the N and I atoms, the Mn—N bonds trans to the I atom are slightly longer than the Mn—N bonds trans to the N atom. The dihedral angle between the approximately planar ligands [maximum deviation = 0.064 (7) Å] is 75.0 (1)°. Numerous inter- and intra­molecular π–π inter­actions between the pyridyl rings are present, the shortest centroid–centroid distance being 3.905 (5) Å. The structure reported herein represents a new monoclinic polymorph of the previously reported monoclinic (P21/c) form [Ha (2011 ▶). Z. Kristallogr. New Cryst. Struct. 226, 187–188].

High-Pressure Study of Oxo-bridged Mixed-Valent MnIII/MnIV Dimers High-Pressure Study of Oxo-bridged Mixed-Valent MnIII/MnIV Dimers

A combination of high-pressure single crystal X-ray diffraction and high-pressure SQUID magnetometry has been used to study two oxo-bridged mixed-valent MnIII/MnIV dimers. [Mn2O2(bpy)4](ClO4)3·3CH3CN, (1·3CH3CN; bpy = 2,2ʹ-bipyridine) has been compressed to 2.0 GPa whilst [Mn2O2(bpy)4](PF6)3·2CH3CN·1H2O, (2·2CH3CN·1H2O) could be measured crystallographically up to 4.55 GPa. The PF6 salt of [Mn2O2(bpy)4]3+ has never been reported before while 1 has been reported as a hydrate and in a different crystallographic space group. The application of hydrostatic pressure imposes significant distortions and modifications in the structures of both complexes. In particular, in complex 1·3CH3CN the Mn-Mn separation is reduced by the contraction of some of the Mn-O bond lengths, whilst in 2·2CH3CN·1H2O the Mn-O-Mn bridging angles and the Mn-O bond lengths are substantially unchanged. Interestingly 2·2CH3CN·1H2O also shows a constant contraction in nearly all the Mn-N bonds. The magnetic behaviour of the complexes has been measured up to 0.87 GPa for 1·3CH3CN and 0.84 GPa for 2·2CH3CN·1H2O.

Bis{2-methoxy-6-[tris(hydroxymethyl)methyliminomethyl]phenolato-κ3O,N,O′}manganese(II) dimethanol solvate hemihydrate

In the title complex, [Mn(C12H16NO5)2]·2CH3OH·0.5H2O, the MnII atom has a distorted octa­hedral coordination geometry in which two N atoms from two 6-meth­oxy-2-[tris­(hydroxy­meth­yl)methyl­imino­meth­yl]phenolate ligands adopt a trans arrangement. The Mn—O(H) bonds (mean length 2.134 Å) are significantly longer than the Mn—O and Mn—N bonds (mean length 2.011 and 2.027 Å, respectively), and the dihedral angle between the mean planes through the aromatic rings of the two ligands is 76.8 (1)°. A complex network of O—H⋯O hydrogen bonds is formed between the complexes and the uncoordinated methanol and water mol­ecules. The C and O atoms of one C—OH group are disordered with equal occupancies.

A novel three-dimensional coordination polymer: poly[di-μ3-acetato-di-μ2-acetato-di-μ3-hydroxido-octa-μ3-triazolato-heptamanganese(II)

The title compound, [Mn7(C2H2N3)8(C2H3O2)4(OH)2]n, is composed of centrosymmetric heptanuclear building units with the central Mn atom on an inversion center. In the building block, three Mn(II) ions are held together by one mu3-hydroxide group, two mu2-triazolate (trz) ligands and two mu2-acetate groups, forming an Mn3 cluster. Two Mn3 clusters are bridged by an Mn atom via two mu2-trz ligands and two mu2-O atoms from two acetate ions to construct a heptanuclear building block. The heptanuclear building units, lying parallel to each other along the b direction, form one-dimensional ladder-like chains and are further interlinked, resulting in a three-dimensional framework through Mn-N(trz) bonds.

A Rare μ-Hydroxo-Bridged Species. Synthesis, Structure, and Properties of μ-Hydroxo(tetraphenylporphyrinatomanganese(III))(phthalocyaninato(azido)chromium(III)), [(TPP)Mn−O(H)−CrPc(N3)

A novel ditetrapyrrolic, heteroleptic, and heterometallic (Mn-Cr) mu-hydroxo-bridged complex has been prepared, and its structural and general properties have been studied. The species mu-hydroxo(tetraphenylporphyrinatomanganese(III))(phthalocyaninato(azido)chromium(III)), [(TPP)Mn-O(H)-CrPc(N3)], isolated as a chloronaphthalene (ClNP) solvate, has been structurally characterized by single-crystal X-ray work. The two (TPP)Mn and CrPc(N3) fragments are held together by the bridging mu-hydroxo ion with long Mn-O [1.993(5) A] and Cr-O [1.976(5) A] bond distances and a Mn-O(H)-Cr angle of 163.7(3) degrees . The five-coordinate Mn center in the (TPP)Mn fragment is displaced from the TPP rigorously planar central N4 core by 0.128 A, and the environment is typical of a Mn(III) high-spin site. The six-coordinate Cr(III) in the CrPc(N3) moiety lies practically in the plane of the phthalocyanine macrocycle (displacement toward the azido group: 0.054 A). The average Mn-N(pyr) and Cr-N(pyr) bond distances are 2.011(6) and 1.982(6) A, respectively, and the Mn-Cr bond distance is 3.929(2) A. The porphyrin and phthalocyanine rings are in an almost eclipsed position [5.16(2) degrees ], and the mean planes of the two macrocycles form a dihedral angle of 5.79(4) degrees. Crystal data for [(TPP)Mn-O(H)-CrPc(N3)].2ClNP, C76H45CrMnN15O.2C10H7Cl: a = 16.645(3) A, b = 17.692(4) A, c = 25.828(5) A, alpha = 90 degrees , beta = 98.79(3) degrees , gamma = 90 degrees , space group P2(1)/c (No. 14), V = 7517(3) A(3), Z = 4, R1 = 0.086, and wR2 = 0.267. IR and UV-vis-near-IR spectral and room temperature magnetic susceptibility data of the [Mn-Cr] species are also presented.

Effect of chemical bonding on the magnetic stability and magnetic moment in Mn-based binary compounds

We study the trend of structural stability and magnetic moment for $\mathrm{Mn}X\phantom{\rule{0.3em}{0ex}}(X=\mathrm{N}$, P, As, and Sb) binary compounds in the NiAs and zinc-blende structures through first-principles spin-density-functional calculations. The exchange splitting and magnetic moment are generally lower in the stable structure, which corresponds to the NiAs structure for MnP, MnAs, and MnSb whereas the zinc-blende structure for MnN. With the exception of MnN, we find the increasing trend of the stability, exchange splitting, and magnetic moment of the ferromanetic state with the anion size along the series MnP, MnAs, and MnSb. Since the N $p$ level is much lower than other anion $p$ levels, the Mn-N bond is more ionic, and thus MnN favors the zinc-blende structure with a lower coordination number. For MnN and MnP with small and light anions, the ground state is an antiferromagnetic state, while a ferromagnetic state is more favorable for MnAs and MnSb, which have larger equilibrium volumes and thereby reduced $p\text{\ensuremath{-}}d$ and $d\text{\ensuremath{-}}d$ couplings for the majority spin channel. Due to the volume and different bonding effects, MnAs and MnSb show a large exchange splitting for the $d$ states and exhibit a nearly half-metallic behavior. The large volume increases the anion $p$-type character near the Fermi level, and thus the ferromagnetic state is stabilized through double exchange interactions.