Polynuclear Manganese Research Articles

Syntheses, paramagnetism, and semiconducting characteristics of polynuclear manganese carbonyl chalcogenide anions: A review

Syntheses, paramagnetism, and semiconducting characteristics of polynuclear manganese carbonyl chalcogenide anions: A review

Evaluation of Manganese Cubanoid Clusters for Water Oxidation Catalysis: From Well-Defined Molecular Coordination Complexes to Catalytically Active Amorphous Films.

With a view to developing multimetallic molecular catalysts that mimic the oxygen‐evolving catalyst (OEC) in Nature's photosystem II, the synthesis of various dicubanoid manganese clusters is described and their catalytic activity investigated for water oxidation in basic, aqueous solution. Pyridinemethanol‐based ligands are known to support polynuclear and cubanoid structures in manganese coordination chemistry. The chelators 2,6‐pyridinedimethanol (H2L1) and 6‐methyl‐2‐pyridinemethanol (HL2) were chosen to yield polynuclear manganese complexes; namely, the tetranuclear defective dicubanes [MnII 2MnIII 2(HL1)4(OAc)4(OMe)2] and [MnII 2MnIII 2(HL1)6(OAc)2] (OAc)2⋅2 H2O, as well as the octanuclear‐dicubanoid [MnII 6MnIII 2(L2)4(O)2(OAc)10(HOMe/OH2)2]⋅3MeOH⋅MeCN. In freshly prepared solutions, polynuclear species were detected by electrospray ionization mass spectrometry, whereas X‐band electron paramagnetic resonance studies in dilute, liquid solution suggested the presence of divalent mononuclear Mn species with g values of 2. However, the magnetochemical investigation of the complexes’ solutions by the Evans technique confirmed a haphazard combination of manganese coordination complexes, from mononuclear to polynuclear species. Subsequently, the newly synthesized and characterized manganese molecular complexes were employed as precursors to prepare electrode‐deposited films in a buffer‐free solution to evaluate and compare their stability and catalytic activity for water oxidation electrocatalysis.

Di-μ-benzoato-di-μ-ethano-lato-tetra-kis-[μ3-5-(hy-droxy-meth-yl)-2-methyl-4-(oxidometh-yl)pyridin-1-ium-3-olato]tetra-kis-[μ3-5-(hy-droxy-meth-yl)-2-methyl-4-(oxidometh-yl)pyridin-3-olato]di-μ3-oxido-hepta-manganese(II,III) ethanol octa-solvate.

Our work in the area of synthesis of polynuclear manganese complexes and their magnetic properties led to the synthesis and crystallization of the title compound, [Mn7(C8H9NO3)4(C8H10NO3)4(C2H5O)2(C7H5O2)2O2]·8C2H5OH. Herein, we report the molecular and crystal structure of the title compound, which was synthesized by the reaction of Mn(C6H5COO)2 with pyridoxine (PNH2, C8H11NO3) followed by the addition of tetra-methyl-ammonium hydroxide (TMAOH). The core of this centrosymmetric complex is a cage-like structure consisting of six MnIII ions and one MnII ion bound together through Mn-O bonds. The compound crystallizes in hydrogen-bonded layers formed by O-H⋯N hydrogen bonds involving the aromatic amine group of the ligand PN2- with the neighboring O atoms from the PNH- ligand. The crystal structure has large voids present in which highly disordered solvent mol-ecules (ethanol) sit. A solvent mask was calculated and 181 electrons were found in a volume of 843 Å3 in one void per triclinic unit cell. This is consistent with the presence of seven ethanol mol-ecules per formula unit, which accounts for 182 electrons per unit cell. Additionally, one ethanol mol-ecule was found to be ordered in the crystal.

Structural characterization and biological evaluation of polynuclear Mn(II) and Cd(II) complexes with 2,2-dimethyl-1,3-propanediamine-N,N,N’,N’-tetraacetate. The influence of ligand structure and counter cation on the complex nuclearity

New polynuclear manganese(II) and cadmium(II) complexes with 2,2-dimethyl-1,3-propanediamine-N,N,N’,N’-tetraacetato ligand (2,2-diMe-1,3-pdta), {Ba[M(2,2-diMe-1,3-pdta)].3H2O}n (M = Mn (1) or Cd (2)) were synthesized and characterized by IR spectroscopy and single-crystal X-ray diffraction analysis. In addition, complex 2 was characterized by solution 1H and 13C NMR spectroscopy. Crystallographic analysis showed that 2,2-diMe-1,3-pdta ligand is hexadentately coordinated to each M(II) ion through the two nitrogen and four carboxylate oxygen atoms, whereas the one of these oxygen atoms is also involved in coordination to the second M(II) ion of the dinuclear [M2(2,2-diMe-1,3-pdta)2]4− unit in polymeric structures. Moreover, three of four carboxylic groups of 2,2-diMe-1,3-pdta ligand are additionally bonded to four Ba(II) ions, in three distinctive bridging coordination modes. Each Ba(II) ion is surrounded by ten oxygen atoms, seven belonging to carboxylate groups of 2,2-diMe-1,3-pdta, and three belonging to water molecules. The coordination environment around Mn(II) and Cd(II) ions could be assigned as a face capped octahedron, while coordination polyhedron around Ba(II) ion in these two complexes was described as a distorted sphenocorona. The antimicrobial potential of complexes 1 and 2 and corresponding metal salts used for their synthesis was evaluated against different bacterial and Candida spp. Both complexes showed selective antifungal activity against the tested Candida spp. compared to the bacterial strains, with the minimal inhibitory concentration (MIC) values in the range 3.12 – 12.50 µM. Moreover, complex 1 caused the slightly decrease of hyphae length, while no significant influence on hyphal length of complex 2 was observed. With aim to assess the therapeutic profile of the complexes, their cytotoxicity was evaluated against the normal human lung fibroblast cell line (MRC-5).

New members of the polynuclear manganese family: MnMn single-molecule magnets and MnMn antiferromagnetic complexes. Synthesis and magnetostructural correlations.

The synthesis, crystal structures and magnetic properties are reported for three novel mixed-valence tetranuclear [MnII2MnIII2(HBuDea)2(BuDea)2(EBA)4] (1), [MnII2MnIII2(HBuDea)2(BuDea)2(DMBA)4] (2) and undecanuclear [MnII3MnIII8O4(OH)2(BuDea)6(DMBA)8] (3) clusters, where H2BuDea is N-butyldiethanolamine, HEBA is 2-ethylbutyric acid and HDMBA is 2,2-dimethylbutyric acid. The compounds have been prepared through self-assembly reactions of manganese(ii) chloride with H2BuDea and respective carboxylic acid in methanol solution in air, affording 1 with HEBA, and 2 or 3 with HDMBA, depending on the experimental conditions. The single crystal X-ray analysis reveals that 1 and 2 have similar centrosymmetric structures based on the {M4(μ3-O)2(μ-O)4} core, while 3 discloses the unprecedented {M11(μ-O)4(μ3-O)12} one. The Mn4 complexes display single-molecule magnet (SMM) behavior with a S = 9 spin ground state and a high energy barrier Ueff/kB of up to 51 K. The magnetic properties of 2 are successfully modeled with JMnIII-MnIII/hc = 25.7 cm-1 and two JMnIII-MnII/hc constants of 3.1 and -0.93 cm-1 (data correspond to the Ĥ = -Jŝ1·ŝ2 formalism). The Mn11 cluster exhibits a paramagnetic behavior with dominant antiferromagnetic coupling. A possible influence of intermolecular effects and of different peripheries of the magnetic cores designed by using 2-ethylbutyrate (in 1) or 2,2-dimethylbutyrate (in 2) on the magnetic properties of 1 and 2 is discussed. The experimental magnetostructural correlations for the {MnII2MnIII2(μ3-O)2(μ-O)4} cores, supported by broken symmetry DFT calculations, disclose the X-MnIIIMnIII angle and MnIII-O distance (where MnIII-X and MnIII-O are axial Jahn-Teller bonds) as the structural factors having the strongest influence on JMnIII-MnIII exchange coupling. It is shown that two JMnIII-MnII constants are necessary for the correct description of magnetic exchange couplings in the {MnII2MnIII2(μ3-O)2(μ-O)4} tetranuclear unit.

Tetra- and dinuclear manganese complexes of xanthene-bridged O,N,O-Schiff bases with 3-hydroxypropyl or 2-hydroxybenzyl groups: ligand substitution at a triply bridging site

Complexation properties of U-shaped ligands, L1 and L2, which are Schiff bases of 5,5'-(9,9-dimethylxanthene-4,5-diyl)bis(salicylaldehyde) (H2xansal) with 3-amino-1-propanol or 2-hydroxybenzylamine, respectively, were investigated to construct polynuclear manganese complexes. In these ligands, two O,N,O-Schiff bases are bridged by a xanthene backbone. The reactions of H4L1 or H4L2 with manganese salts afforded tetra- and dinuclear manganese complexes, including the tetramanganese(ii,ii,iii,iii) complex [Mn4(L1)2(μ-OAc)2] with a Mn4O6 core exhibiting an incomplete double-cubane structure. In the Mn4O6 core, phenolate and alkoxide O atoms bridge the manganese ions. Deprotonated 3-hydroxypropyl groups were crucial to the assembly of four manganese ions because the phenolate-bridged dimanganese(iii,iii) complex [Mn2(H2L1)2]2+ was obtained in the absence of a base, and H4L2, which has 2-hydroxybenzyl groups instead of 3-hydroxypropyl groups in H4L1, afforded the cyclic dimanganese(iv,iv) complex [Mn2(L2)2]. We disclosed that [Mn4(L1)2(μ-OAc)2] was converted to the oxo-bridged tetramanganese(iii,iii,iii,iii) complex [Mn4(L1)(HL1)(μ3-O)(μ-OAc)2]+ by treating with NH4PF6 or NH4BF4: a triply bridging alkoxide was protonated and replaced by an oxide ligand. The cyclic voltammograms of [Mn4(L1)(HL1)(μ3-O)(μ-OAc)2]+ suggested that the reverse reaction forming [Mn4(L1)2(μ-OAc)2] occurred in the electrochemical processes and was assisted by protonation.

Correlating Bridging Ligand with Properties of Ligand-Templated [MnII3X3]3+ Clusters (X = Br-, Cl-, H-, MeO-).

Polynuclear manganese compounds have garnered interest as mimics and models of the water oxidizing complex (WOC) in photosystem II and as single molecule magnets. Molecular systems in which composition can be correlated to physical phenomena, such as magnetic exchange interactions, remain few primarily because of synthetic limitations. Here, we report the synthesis of a family of trimanganese(II) complexes of the type Mn3X3L (X = Cl-, H-, and MeO-) where L3- is a tris(β-diketiminate) cyclophane. The tri(chloride) complex (2) is structurally similar to the reported tri(bromide) complex (1) with the Mn3X3 core having a ladder-like arrangement of alternating M-X rungs, whereas the tri(μ-hydride) (3) and tri(μ-methoxide) (4) complexes contain planar hexagonal cores. The hydride and methoxide complexes are synthesized in good yield (48% and 56%) starting with the bromide complex employing a metathesis-like strategy. Compounds 2-4 were characterized by combustion analysis, X-ray crystallography, X-band EPR spectroscopy, SQUID magnetometry, and infrared and UV-visible spectroscopy. Magnetic susceptibility measurements indicate that the Mn3 clusters in 2-4 are antiferromagnetically coupled, and the spin ground state of the compounds (S = 3/2 (1, 2) or S = 1/2 (3, 4)) is correlated to the identity of the bridging ligand and structural arrangement of the Mn3X3 core (X = Br, Cl, H, OCH3). Electrochemical experiments on isobutyronitrile solutions of 3 and 4 display broad irreversible oxidations centered at 0.30 V.

Discrete polynuclear manganese(ii) complexes with thiacalixarene ligands: synthesis, structures and photophysical properties.

The synthesis, crystal structure and photophysical properties of the new compound [Mn4(ThiaSO2)2F][K(18-crown-6)], ThiaSO2 = p-tert-butylsulphonylcalix[4]arene, are presented and compared to the ones of [Mn4(ThiaSO2)2F]K. The strong orange luminescence is attributed to the Mn(2+) centred (4)T1→(6)A1 transition. Its temperature and pressure dependence and quenching by molecular dioxygen are reported. The latter is attributed to energy transfer from the (4)T1 state exciting dioxygen to its (1)∑(+)g state. In the solid state, the quenching is much more efficient in [Mn4(ThiaSO2)2F][K(18-crown-6)] than in [Mn4(ThiaSO2)2F]K. This is attributed to the open pore structure of the former allowing fast diffusion of dioxygen into the crystal lattice.

Synthesis, Structure, and Catalytic Epoxidation Property of a New Phenolato and μ1,1,3-Azido Co-Bridged Polynuclear Manganese(III) Complex Derived from N,N′-Bis(5-methylsalicylidene)ethane-1,2-diamine

A new phenolato and μ1,1,3-azido co-bridged polynuclear manganese(iii) complex has been synthesised and characterised. The structure of the complex has been confirmed by single crystal X-ray diffraction analyses. The ability of the complex to catalyse the epoxidation of styrene using PhIO or NaOCl as oxidant has been studied. Results show the catalysis to occur efficiently in the presence of PhIO and NaOCl.

Formation of octapod MnO nanoparticles with enhanced magnetic properties through kinetically-controlled thermal decomposition of polynuclear manganese complexes

Polynuclear manganese complexes are used as precursors for the synthesis of manganese oxide nanoparticles (MnO NPs). Altering the thermal decomposition conditions can shift the nanoparticle product from spherical, thermodynamically-driven NPs to unusual, kinetically-controlled octapod structures. The resulting increased surface area profoundly alters the NP's surface-dependent magnetism and may have applications in nanomedicine.

A Spin-Canted Polynuclear Manganese Complex Comprised of Alternating Linkage of Cyclic Tetra-and Mononuclear Fragments

A polynuclear manganese complex composed of alternating cyclic tetramer and monomer has been solvothermally prepared and magnetically characterized. Magnetic analyses indicate that the title compound shows spin-canting behavior.

Synthesis, X-ray crystal structure, and electrochemistry of polynuclear azido-bridged manganese(III) and copper(II) Schiff base complexes

Abstract New azido-bridged [MnIII(salabza)(μ-1,3-N3)]n (1), and [CuII4(salabza)2(μ-1,1-N3)2(N3)2(HOCH3)2],(2) complexes with an unsymmetrical Schiff base ligand, {H2salabza = N,N’-bis(salicylidene)-2-aminobenzylamine}, have been synthesized, characterized by spectroscopic and electrochemical methods, and their crystal structures have been determined by X-ray diffraction. In complex 1, each manganese(III) atom is coordinated with N2O2 donor atoms from salabza and two adjacent Mn(III) centers are linked by an end-to-end (EE) azide bridge to form a helical polymeric chain with octahedral geometry around the Mn(III) centers. Complex 2 is a centrosymmetric tetranuclear compound containing two types of Cu(II) centers with square pyramidal geometry. Each terminal copper atom is surrounded by N2O2 atoms of a salabza ligand, and the oxygen atom of the methanol molecule. Each central copper(II) ion is coordinated with two phenoxo oxygen atoms from one salabza, one terminal azido, and two end-on (EO) bridging azido ligands. The central copper(II) ions are linked to each other by the two end-on (EO) azido groups.

Coordination Polymers Containing Manganese(II)-Azido Layers Connected by Dipyridyl-tetrazine and 4,4′-Azobis(pyridine) Linkers

Two new polynuclear manganese(II) complexes [Mn(dptz)(N(3))(2)](n) (1) and [Mn(azpy)(N(3))(2)](n) (2) (where dptz = dipyridyl-tetrazine and azpy = 4,4'-azobis(pyridine)) have been synthesized by self-assembly of the ligand azide, together with dptz and azpy as secondary spacers. The compounds are characterized by single-crystal X-ray diffraction analyses and variable-temperature magnetic measurements. The structural analyses reveal that in complex 1, which is the first reported Mn(II) complex with the ligand dptz, two μ(1,3) bridging azides connect neighboring manganese ions in a zigzag manner to generate a neutral two-dimensional (2D) sheet which is further connected by the dptz ligands to form a three-dimensional (3D) framework. By contrast, complex 2 contains dimeric [Mn(2)(μ(1,1)-N(3))(2)](2+) fragments linked to four identical motifs by means of four single μ(1,3)-N(3) bridges, that generates a neutral 2D Mn(II)-azide sheet which is further interconnected by azpy ligands to neighboring manganese ions forming an unprecedented 3D network. Variable-temperature (2-300 K) magnetic susceptibility measurements show the presence of predominantly antiferromagnetic coupling for both complexes that has been reproduced with a regular antiferromagnetic S = 5/2 chain (J) with interchain interactions (j) modeled with the molecular field approximation with J = -7.1 cm(-1) and j' = -0.8 cm(-1) for 1 and J = -4.2 cm(-1) and j' = 0.1 cm(-1) for 2.

A facile “bottom-up” approach to prepare free-standing nano-films based on manganese coordination clusters

We present herein a novel method to prepare free-standing Dried Foam Films (DFFs) whereby individual polynuclear manganese complexes cover quantitatively the holes of micro-grids; the fabricated, homogeneous films have a cross-sectional thickness of only ca. 5 nm and are characterised by high mechanical stability.

Two different coordination geometries in polynuclear manganese(II) complexes with bis(μ-phosphinato) bridges

Four new polynuclear phosphinato-bridged manganese(II) complexes, three dinuclear compounds [Mn(μ-dpp)(5-dmbpy)(NO3)]2 (1), [Mn(μ-dpp)(Me-phen)(NO3)]2 (2), [Mn(μ-bmp)(neocuproine)(NO3)]2 (3) and a 1D compound [Mn(μ-bmp)2]n (4) where Hdpp is diphenylphosphinic acid, Hbmp is bis(4-methoxyphenyl)phosphinic acid, 5-dmbpy=5,5′-dimethyl-2,2′-dipyridyl, Me-phen=methyl-1,10-phenanthroline and neocuproine=2,9-dimethyl-1,10-phenanthroline, have been synthesized and structurally characterized by X-ray crystallography. In this series, the dinuclear structures consist in a bis(diphenylphosphinato) (dpp) or a bis(4-methoxyphenyl)phosphinato (bmp) anion bridging the two Mn(II) centers in a syn–syn coordination mode for 1–3. The monodimensional compound 4 is built from double bridging syn–syn bis(4-methoxyphenyl)phosphinato anions. The coordination geometry around the Mn(II) ions in 1–3 is six-coordinate with distorted octahedral environment. Moreover, the coordination geometry around the Mn(II) ions in 4 is tetrahedral. The magnetic behavior of these complexes is reported. The complexes show weak antiferromagnetic coupling with J in the range 0.05–0.43cm−1 for 1–3 and 0.88cm−1 for 4. The magnetic properties are discussed in relation to the structural data.

‘Old’ Clusters with New Function: Oxidation Catalysis by High Oxidation State Manganese and Cerium/Manganese Clusters Using O2 Gas

The family of polynuclear manganese clusters of formula [Mn(12)O(12)(O(2)CR)(16)(H(2)O)(4)] (R = Et, Ph, etc.) has been investigated in great detail over the years for their ability to function as single-molecule magnets (SMMs), but they have not been employed as oxidation catalysts. In the present report, the ability is described of these clusters to act as catalysts in the selective oxidation of benzyl alcohol to benzaldehyde using molecular O(2) as the primary oxidant and the nitroxyl radical TEMPO as a cocatalyst. A systematic investigation of Mn clusters varied in their R group, oxidation state, and size was conducted in order to realize the electronic requirements that will lead to the best catalytic activity. The best reactivity (>99%) was obtained when the catalyst was the mixed-metal cluster [CeMn(6)O(9)(O(2)CMe)(9)(NO(3))(H(2)O)(2)], which contains Ce(4+)Mn(4+)(6) ions; in this case, lower loadings of catalysts (cluster and TEMPO) are required and the reaction can proceed even without a solvent. In addition, it has been demonstrated that the high efficiency can be only achieved when both high oxidation Ce(4+) and Mn(4+) ions are present within the same cluster.

Control of molecular architecture by steric factors: mononuclear vs polynuclear manganese(iii) compounds with tetradentate N2O2 donor Schiff bases

Three manganese(III) compounds, [Mn(III)(vanoph)(DMF)(H(2)O)]ClO(4) (1), [Mn(III)(vanoph)(N(3))(H(2)O)]·2H(2)O (2) and [Mn(III)(saloph)(μ(1,3)-N(3))](n) (3), where H(2)vanoph = N,N'-(1,2-phenylene)-bis(3-methoxysalicylideneimine), H(2)saloph = N,N'-(1,2-phenylene)-bis(salicylideneamine) are tetradentate N(2)O(2) ligands and DMF = N,N-dimethylformamide, have been prepared and characterised by elemental analysis, IR and UV-Vis spectroscopy and single-crystal X-ray diffraction studies. Compounds 1 and 2 are monomeric but compound 3 consists of a chain system with the repeating unit [Mn(III)(saloph)(N(3))] bridged by μ-1,3 azide. Compound 1 crystallises in monoclinic space group P2(1)/n with cell dimensions of a = 11.1430(2), b = 16.3594(3), c = 15.4001(3) Å, β = 108.417(1), Z = 4 whereas compounds 2 and 3 crystallise in orthorhombic space groups Pbca and Pna2(1), respectively, with cell dimensions of a = 16.069(3), b = 15.616(3), c = 18.099(4) Å, Z = 8 (for 2) and a = 18.760(9), b = 13.356(5), c = 6.616(3) Å, Z = 4 (for 3). In all the compounds, Mn(III) has a six-coordinated pseudo-octahedral geometry in which O(2), O(3), N(1) and N(2) atoms of the deprotonated di-Schiff base constitute the equatorial plane. In both compounds 1 and 2, water molecules are present in the fifth coordination sites in the apical positions. The sixth coordination sites are occupied by one O atom of a solvent DMF in compound 1 and an N atom of azide in compound 2. The coordinated water initiates hydrogen-bonded networks in both compounds 1 and 2 to form well-isolated supramolecular dimers. At room temperature the χ(M)T values for the compounds 1 and 2 remain almost constant until 30 K. Below this temperature, the χ(M)T values drastically drop to 0.72 cm(3) mol(-1) K for 1 and 0.52 cm(3) mol(-1) K for 2. The best fits were obtained with J = -0.92 cm(-1), |D| = 2.05 cm(-1), g = 2.0 and R = 8.1 × 10(-4) for 1 and J = -1.16 cm(-1), |D| = 2.05 cm(-1), g = 2.0 and R = 1.2 × 10(-3) for 2. However, in compound 3, two axial positions are occupied by the azide ions. The Mn···Mn repeating distance is 6.616 Å along the chain. Magnetic characterisation shows that the μ(1,3)-bridging azide ion mainly transmits an antiferromagnetic interaction (J = -6.36 cm(-1)) between Mn(III) ions. The presence of two methoxy groups increases the steric crowding in the H(2)vanoph moiety and thereby inhibits the formation of a polynuclear compound with this ligand.

Syntheses, structures and magnetic properties of μ 1,5-dicyanamide bridged di- and polynuclear manganese(II) complexes containing neutral N-donor Schiff bases: Control of coordination number and nuclearity by varying denticity

Two hexacoordinated dinuclear compounds [Mn(L1)(dca)] 2(ClO 4/PF 6) 2·CH 3OH ( 1/2) and two heptacoordinated coordination polymers [Mn(L2)(dca)] n (ClO 4/PF 6) n ( 3/ 4) [L1 = N, N′-(bis-(pyridin-2-yl)benzylidene)-1,3-propanediamine; L2 = N, N′-(bis-(pyridin-2-yl)benzylidene)diethylenetriamine; dca = dicyanamide] are synthesized and characterized. Structures of 1– 3 have been solved by X-ray diffraction measurements. Each manganese(II) center in 1/ 2 is located in a distorted octahedral environment with an MnN 6 chromophore coordinated by the four N atoms of L1 and two nitrile N atoms of bibridged μ 1,5 dca. Interestingly, the coordination polymer 3 forms a 1D chain through single Mn–(NCNCN)–Mn units in which each manganese(II) center adopts a pentagonal bipyramidal geometry with an MnN 7 chromophore occupied with five N atoms of L2 and two nitrile N atoms of monobridged μ 1,5 dca. Magnetic susceptibility measurements of 1– 3 in the 2–300 K temperature range reveal weak antiferromagnetic interactions.

Functionalized Sandwich-Type Polyoxometalates Based on the Polynuclear Manganese Cluster and Imidazole Ligands

Two polynuclear manganese(II) sandwiched heteropolytungstates, Na10(HC3H4N2){[Na(H2O)][Mn(C3H4N2)]3[SbW9O33]2}·20H2O (1) and (C4H7N2)10[Mn4(H2O)2(PW9O34)2] (2), have been obtained by conventional aqueous synthesis method and characterized by IR spectra, TG, elemental analyses and single crystal X-ray diffraction. In compound 1, the three-nuclear manganese cluster is sandwiched by two [B-α-SbW9O33]9− units, and each manganese (II) is coordinated by one imidazole (im) molecule. Differently, compound 2 has a four-nuclear manganese (II) cluster with two coordination water molecules. The 2-methylimidazole (mim) molecules float around the polyanions and connect them into a 3D supramolecular framework by hydrogen bondings. The magnetic investigation for compound 1 indicates the existence of weak antiferromagnetic interaction in the sandwiched three-nuclear [Mn(C3H4N2)]3 cluster.

Solvent control on the structural versatility and properties of manganese(II) complexes surrounded by the flexible hinge-like ligand

Four different types of polynuclear manganese(II) compounds with bhnq2− bridges were obtained from the reaction of Mn(CH3COO)2·4H2O with the flexible hinge-like ligand H2bhnq (H2bhnq = 2,2′-bi(3-hydroxy-1,4-naphthoquinone)) by controlling the reaction solvent: [Mn3(bhnq)3(H2O)2]·10.5H2O (1), [Mn2(bhnq)2(DMSO)4]·2DMSO·CHCl3 (2), {[Mn(bhnq)(H2O)2]·2H2O}n (3), and {[Mn(bhnq)(DMF)2]}n (4). All complexes are neutral with the same Mn/bhnq 1:1 formulation ratio. Compounds 1 and 2 are discrete systems, while compounds 3 and 4 are one-dimensional ones. All compounds were characterized by X-ray diffraction and show different coordination modes for the bhnq2− ligand.