Halogen-Dependent Diversity and Weak Interactions in the Heterometallic Ni/Cd Complex Solids: Structural and Theoretical Investigation

Three novel heterometallic Ni/Cd coordination compounds [Ni(en)3][CdCl4]∙3dmso (1), [Ni(en)2(dmf)2][CdBr4] (2), and [Ni(en)3]2[CdI4](I)2 (3) have been synthesized through the self-assembly process in a one-pot reaction of cadmium oxide, nickel salt (or nickel powder), NH4X (X = Cl, Br, I), and ethylenediamine in non-aqueous solvents dmso (for 1) or dmf (for 2 and 3). Formation of the one- (1) or three-dimensional (2 and 3) hydrogen-bonded frameworks has been observed depending on the nature of the [CdX4]2- counter-anion, as well as on the nature of the solvent. The electronic structures of [Ni(en)3]2+ and [Ni(en)2(dmf)2]2+ cations were studied at the DFT and CASSCF levels, including the ab initio ligand field theory (AILFT) calculations. The non-covalent intermolecular contacts between the cationic nickel and anionic cadmium blocks in the solid state were investigated by the QTAIM analysis. The mechanism of ligand substitution at the nickel center in [Ni(en)2(dmf)2]2+ was theoretically investigated at the ωB97X-D4/ma-def2-TZVP//DLPNO-CCSD(T)/ma-def2-TZVPP level. The results demonstrate that thermodynamic factors are structure-determining ones due to low energy barriers of the rotation of dmf ligands in [Ni(en)2(dmf)2]2+ (below 3 kcal mol-1) and the reversible transformation of [Ni(en)2(dmf)2]2+ into [Ni(en)3]2+ (below 20 kcal mol-1).

Supramolecular Diversity, Theoretical Investigation and Antibacterial Activity of Cu, Co and Cd Complexes Based on the Tridentate N,N,O-Schiff Base Ligand Formed In Situ

The four new complexes, [Cu(HL¹)(L²)Cl] (1), [Cu(HL¹)(L¹)]∙Cl∙2H₂O (2), [Co(L¹)₂]∙Cl (3) and [Cd(HL¹)I₂]∙dmso (4), have been prepared by one-pot reactions of the respective chloride or iodide metal salt with a non-aqueous solution of the polydentate Schiff base, HL¹, resulted from in situ condensation of benzhydrazide and 2-pyridinecarboxaldehyde, while a ligand HL², in case of 1, has been formed due to the oxidation of 2-pyridinecarboxaldehyde under reaction conditions. The crystallographic analysis revealed that the molecular building units in 1-4 are linked together into complex structures by hydrogen bonding, resulting in 1D, 2D and 3D supramolecular architectures for 1, 2 and 4, respectively, and the supramolecular trimer for 3. The electronic structures of 1-4 were investigated by the DFT theoretical calculations. The non-covalent interactions in the crystal structures of 1-4 were studied by means of the Hirshfeld surface analysis and the QTAIM theory with a special focus on the C-H⋯Cl bonding. From the DFT/DLPNO-CCSD(T) calculations, using a series of charged model {R₃C-H}⁰⋯Cl^- assemblies, we propose linear regressions for assessment of the interaction enthalpy (ΔH, kcal mol^-1) and the binding energy (BE, kcal mol^-1) between {R₃C-H}⁰ and Cl^- sites starting from the electron density at the bond critical point (ρ(r_BCP), a.u.): ΔH = -678 × ρ(r) + 3 and BE = -726 × ρ(r) + 4. It was also has been found that compounds 1, 3 and 4 during in vitro screening showed an antibacterial activity toward the nine bacteria species, comprising both Gram-positive and Gram-negative, with MIC values ranging from 156.2 to 625 mg/L. The best results have been obtained against Acinetobacter baumannii MβL.

A novel o-vanillin Fe(III) complex catalytically active in C-H oxidation: exploring the magnetic exchange interactions and spectroscopic properties with different DFT functionals

The novel complex [Fe^IIICl(L)₂(H₂O)] (1) was synthesized by interaction of iron(III) chloride with ethanol solution of o-vanillin (HL) and characterized by IR, UV/Vis spectroscopy, thermogravimetry and single crystal X-ray diffraction analysis. The molecules of 1 in the solid state are joined into supramolecular dimeric units, where a set of strong hydrogen bonds predefines the structure of the dimer according to the "key-lock" principle. From the Hirshfield surface analysis the contribution of π⋯π stacking to the overall stabilization of the dimer was found to be negligible. Broken symmetry DFT calculations suggested the presence of long-range antiferromagnetic interactions (J = -0.12 cm^-1 for H = -JS₁S₂ formalism) occurring through the Fe-O⋯O-Fe pathway, as evidenced by the studies of the model dimers where the water molecules were substituted by acetonitrile and acetone ones. The benchmark studies using a set of literature examples and various DFT functionals revealed the hybrid-GGA B3LYP as the best one for prediction of Fe^III⋯Fe^III antiferromagnetic exchange couplings of small magnitude. Magnetic susceptibility measurements confirmed antiferromagnetic coupling between the metal atoms in 1 with a coupling constant of -0.35 cm^-1. Catalytic studies demonstrated that 1 acts as an efficient catalyst in the oxidation of cyclohexane with hydrogen peroxide in the presence of nitric acid promoter and under mild conditions (yield up to 37% based on the substrate), while tert-butylhydroperoxide (TBHP) and m-chloroperoxybenzoic acid (m-CPBA) as oxidants exhibit less efficiency. Combined UV/TDDFT studies evidence the structural rearrangement of 1 in acetonitrile with the formation of [Fe^IIICl(L)₂(CH₃CN)] species. The TDDFT benchmark using nine common DFT functionals and two model compounds (o-vanillin and [Fe^III(H₂O)₆]³⁺ ion) support the hybrid meta-GGA M06-2X functional as the one most correctly predicting the excited state structure for the Fe(III) complexes, under the conditions studied.

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.

Phenoxazinone synthase-like catalytic activity of novel mono- and tetranuclear copper(ii) complexes with 2-benzylaminoethanol

Three novel coordination compounds, [Cu(ca)2(Hbae)2] (1), [Cu(va)2(Hbae)2] (2) and [Cu4(va)4(bae)4]·H2O (3), have been prepared by self-assembly reactions of copper(ii) chloride (1 and 2) or tetrafluoroborate (3) and CH3OH (1 and 3) or CH3CN (2) solution of 2-benzylaminoethanol (Hbae) and cinnamic (Hca, 1) or valeric (Hva, 2 and 3) acid. Crystallographic analysis revealed that both 1 and 2 have mononuclear crystal structures, wherein the complex molecules are H-bonded forming extended supramolecular chains. The tetranuclear structure of 3 is based on the {Cu4(μ3-O)4} core, wherein the metal atoms are bound together by μ3 oxygen bridges from 2-benzylaminoethanol forming an overall cubane-like configuration. The strong hydrogen bonding in 1-3 leads to the joining of the neighbouring molecules into 1D chains. Concentration-dependent ESI-MS studies disclosed the equilibria between di-, tri- and tetranuclear species in solutions of 1-3. All three compounds act as catalysts for the aerobic oxidation of o-aminophenol to the phenoxazinone chromophore (phenoxazinone synthase-like activity), with the maximum reaction rates of 4.0 × 10-7, 2.5 × 10-7 and 2.1 × 10-7 M s-1 for 1, 2 and 3, respectively, supported by the quantitative yield of the product after 24 h. The dependence of the reaction rates on catalyst concentrations is evidence of reaction orders higher than one relative to the catalyst. Kinetic and ESI-MS data allowed us to assume that the tetranuclear species, originating from 1, 2 and 3 in solution, possess considerably higher activity than the species of lower nuclearity. Mechanistic and isotopic 18O-labelling experiments suggested that o-aminophenol coordinates to CuII species with the formation of reactive intermediates, while the oxygen from 18O2 is not incorporated into the phenoxazinone chromophore.

Co-existence of ferro- and antiferromagnetic interactions in a hexanuclear mixed-valence CoMnMn cluster sustained by a multidentate Schiff base ligand

The successful utilization of the "direct synthesis" approach yielded the unprecedented hexanuclear complex of formula [Co₂MnMn(L¹)₄Cl₂(μ₃-O)₂(dmf)₄]·2dmf (1) (H₃L is the Schiff base derived from the condensation of salicylaldehyde and 3-aminopropane-1,2-diol). Single crystal X-ray analysis revealed that 1 crystallizes in the monoclinic system P2₁/c and it contains a rare mixed-valence {CoMnMn(μ₂-O)₈(μ₃-O)₂} core where all metal ions are linked through the phenolato and alkoxo groups of the L^3- ligand. Besides the charge balance resulting from the X-ray structure, the oxidation state of the metal ions has been confirmed by XPS spectroscopy. Cryomagnetic studies indicate the coexistence of ferro- (Mn^IV-Mn^II, J₂ = +1.10(3) cm^-1, J₃ = +2.19(3) cm^-1; Mn^II-Mn^II, j = +0.283(3) cm^-1) and antiferromagnetic interactions (Mn^IV-Mn^IV, J₁ = -17.31(4) cm^-1), with the six-coordinate Co^III ions being diamagnetic. DFT type calculations were carried out to substantiate these values. The energy diagram for the different spin states using the best-fit parameters shows the occurrence of six low-lying spin states (S = 0-5) which are close in energy but clearly separated from the remaining ones, with the ground spin state being S = 5. Complex 1 is found to be the first example where weak ferromagnetic exchange between Mn^II ions through the long -O-Mn^IV-O- pathway takes place.

Heterometallic CoIIIZnII Schiff Base Catalyst for Mild Hydroxylation of C(sp3)–H Bonds of Unactivated Alkanes: Evidence for Dual Mechanism Controlled by the Promoter

The novel Schiff base complex [CoIIIZnIIL3Cl2]·CH3OH (1) was synthesized by interaction of zinc powder, cobalt(II) chloride and methanol solution of the pre-formed HL in air (HL is the product of condensation of o-vanillin and methylamine) and characterized by IR, UV-Vis and NMR spectroscopy, ESI-MS and single crystal X-ray diffraction analysis. In the heterometallic core of 1 the two metal centers are bridged by deprotonated phenoxy groups of the L− ligands with the cobalt-zinc separation of 3.123 Å. Catalytic investigations demonstrated a pronounced activity of 1 towards mild alkane oxidation with m-chloroperbenzoic acid (m-CPBA) as an oxidant and cis-1,2-dimethylcyclohexane (cis-1,2-DMCH) as the model substrate. The influence of the nature of different promoting agents of various acidities (from HOTf to pyridine) on the catalytic process was studied in detail and a pronounced activity of 1 in the presence of nitric acid promoter was found, also showing a high retention of stereoconfiguration of the substrate (>99% for cis-1,2-DMCH). The best achieved yield of tertiary cis-alcohol based on the oxidant was 61%, with a turnover number (TON) of 198 for nitric acid as promoter. The 18O-incorporations into the alcohols when the reactions were performed under 18O2 atmosphere using acetic and nitric acid promoters, suggest that the cis-1,2-DMCH hydroxylation proceeds by two distinct pathways, a non-stereoselective and a stereoselective one (with and without involvement of a long-lived free carbon radical, respectively). The former dominates in the case of acetic acid promoter and the latter is realized in the case of HNO3 promoter.

Copper-containing hybrid compounds based on extremely rare [V2Mo6O26]6– POM as water oxidation catalysts

Hybrid Cu/V/Mo compounds with rare [α-V₂Mo₆O₂₆]^6– and oxides prepared by their thermal degradation were used as catalysts for water oxidation.

Copper(II) Complexes with Bulky N-Substituted Diethanolamines: High-Field Electron Paramagnetic Resonance, Magnetic, and Catalytic Studies in Oxidative Cyclohexane Amidation

The novel coordination compounds [Cu₂(H ^tBuDea)₂(OAc)₂] (1) and [Cu₂(H ⁿBuDea)₂Cl₂]· nH₂O (2) have been prepared through the reaction of the respective copper(II) salts with N- tert-butyldiethanolamine (H₂ ^tBuDea, for 1) or N-butyldiethanolamine (H₂ ⁿBuDea, for 2) in methanol solution. Crystallographic analysis reveals that, in spite of the common binuclear {Cu₂(μ-O)₂} core, the supramolecular structures of the complexes are drastically different. In 1 binuclear molecules are linked together by H-bonds into 1D chains, while in 2 the neighboring pairs of binuclear molecules are H-bonded, forming tetranuclear aggregates. Variable-temperature (1.8-300 K) magnetic susceptibility measurements of 1 and 2 show a dominant antiferromagnetic behavior. Both complexes are also studied by HF-EPR spectroscopy. While the interaction between Cu(II) centers in 1 can be described by a single coupling constant J = 130.1(3) cm^-1 (using H = JS₁ S₂), the crystallographically different {Cu₂(μ-O)₂} pairs in 2 are expected exchange from ferro- to antiferromagnetic behavior (with J ranging from -32 to 110 cm^-1, according to DFT calculations). Complexes 1 and 2 act as catalysts in the amidation of cyclohexane with benzamide, employing ^tBuOO ^tBu as oxidant. The maximum achieved conversion of benzamide (20%, after 24 h reaction time) was observed in the 1/ ^tBuOO ^tBu system. In the cases of ^tBuOO(O)CPh or ^tBuOOH oxidants, no significant amidation product was observed, while for ^tBuOO(O)CPh, the oxidative dehydrogenation of cyclohexane occurred, giving cyclohexene, to afford the allylic ester (cyclohex-2-en-1-yl benzoate) as the main reaction product.

Heterometallic CuIIFeIII and CuIIMnIII alkoxo-bridged complexes revealing a rare hexanuclear M6(μ-X)7(μ3-X)2 molecular core

The novel hexanuclear complexes [Cu4Fe2(OH)(Piv)4(tBuDea)4Cl]·0.5CH3CN (1) and [Cu4Mn2(OH)(Piv)4(tBuDea)4Cl] (2) were prepared through one-pot self-assembly reactions of copper powder and iron(ii) or manganese(ii) chloride with N-tert-butyldiethanolamine (H2tBuDea) and pivalic acid (HPiv) in acetonitrile. Crystallographic studies revealed the uncommon molecular core type M6(μ-X)7(μ3-X)2 in 1 and 2, which can be viewed as a combination of two trimetallic M3(μ-X)2(μ3-X) fragments joined by three bridging atoms. The analysis and classification of the hexanuclear complexes having a M3(μ-X)2(μ3-X) moiety as a core forming fragment using data from the Cambridge Structural Database (CSD) were performed. Variable-temperature (1.8-300 K) magnetic susceptibility measurements of 1 showed a decrease of the effective magnetic moment value at low temperature, indicative of antiferromagnetic coupling between the magnetic centres (JFe-Cu/hc = -6.9 cm-1, JCu-Cu/hc = -4.1 cm-1, JFe-Fe/hc = -24.2 cm-1). Complex 1 acts as a catalyst in the reaction of mild oxidation of cyclohexane with H2O2, showing the yields of products, cyclohexanol and cyclohexanone, up to 17% using pyrazinecarboxylic acid as a promoter. In the oxidation of cis-1,2-dimethylcyclohexane with m-chloroperoxybenzoic acid (m-CPBA), 70% of retention of stereoconfiguration was observed for tertiary alcohols. Compound 1 also catalyses the amidation of cyclohexane with benzamide. In all three catalytic reactions the by-products were investigated in detail and discussed.

Three different types of bridging ligands in a 3d-3d'-3d'' heterotrimetallic chain

A one-pot synthesis of a 3d-3d'-3d'' heterotrimetallic coordination polymer with double diphenoxido, single cyanido and bis-bidentate oxalate as alternating bridges which exhibits an overall antiferromagnetic behaviour has been developed.

Heterotrimetallic complexes in molecular magnetism

The most representative examples of coordination compounds containing three different paramagnetic metal ions are reviewed, with a special emphasis on their magnetic properties.

Details make the difference: a family of tetranuclear CuIIMnIII complexes with cube-like and double open cube-like cores

The "direct synthesis" approach, namely one-pot reaction of metal powders and ammonium salt with a methanol solution of a polydentate Schiff base (H₂L) formed in situ from salicylaldehyde and ethanolamine, has been successfully used for the preparation of the new heterometallic compounds [Cu₃Mn(L)₄(CH₃OH)₃]I₃ (1), [Cu₃Mn(L)₄(CH₃OH)₃(H₂O)]NCS·H₂O (2), [Cu₃Mn(L)₄(CH₃OH)(H₂O)_2.55]Br·0.45H₂O (3) and [Cu₃Mn(L)₄(H₂O)_3.4]BF₄·0.6H₂O (4). Crystallographic analysis revealed that 1-4 are based on the tetranuclear core {CuMn^III(μ₃-O)₄} where the metal centres are joined by the oxygen bridges of Schiff base ligands forming a cube-like arrangement. The novel heterometallic compound [Cu₃Mn(L)₄(CH₃OH)₃]₂[Mn(NCS)₄]·2CH₃OH (5) has been obtained by the "building block" approach using the reaction of [Cu(HL)₂] with manganese acetate and NH₄NCS in methanol. The crystal structure of 5 revealed the {CuMn^III(μ-O)₂(μ₃-O)₂} metal core which can be viewed as a double open cube. In spite of a similar {Cu₃MnO₄} atom set in the cores of 1-5, the complexes show rather different molecular structures and significantly differ by the number and combinations of coordinated CH₃OH/H₂O solvent molecules. Variable-temperature (2-300 K) magnetic susceptibility along with variable-field magnetization measurements of 1-5 showed a decrease of the effective magnetic moment value at low temperature, indicative of the antiferromagnetic coupling of medium size (-55 to -22 cm^-1). For these systems resembling a compressed prism the coupling constant in walls J₄ correlates with the averaged bonding angles in walls α: J₄vs. α develops approximately according to a straight line.

Field-Assisted Slow Magnetic Relaxation in a Six-Coordinate Co(II)-Co(III) Complex with Large Negative Anisotropy

The reaction of Co(CH₃COO)₂·4H₂O with the Schiff base ligand LH₄ derived from o-vanillin and tris(hydroxymethyl)aminomethane produces the dinuclear mixed-valence complex [Co^IICo^III(LH₂)₂(CH₃COO)(H₂O)](H₂O)₃ (1), which has been investigated using IR spectroscopy, X-ray crystallography, temperature-dependent magnetic susceptibility, magnetization, HFEPR spectroscopy, and ac susceptibility measurements at various frequencies, temperatures, and external magnetic fields. The structure of 1 consists of neutral molecules in which two cobalt ions with distorted octahedral geometries, Co^IIO₆ and Co^IIIN₂O₄, are bridged by two deprotonated -CH₂O^- groups of the two LH₂^2- ligands. 1 completes a series with Cl, Br, NO₃, and NCS anions published before by different authors. Low-temperature HFEPR measurements reveal that the ground electronic state of the Co(II) center in 1 is a highly anisotropic Kramers doublet; the effective g values of 7.18, 2.97, and 1.96 are frequency-independent over the frequency ranges 200-630, 200-406, and 200-300 GHz for the highest, intermediate, and lowest g_eff values, respectively. The two lower values were not seen at higher frequencies because the magnetic field was not high enough. Temperature-dependent magnetic susceptibility and field-dependent magnetization data confirm high magnetic anisotropy of the easy axis type. Complex 1 behaves as a single-ion magnet under a small applied external field and demonstrates two relaxation modes that strongly depend on the applied static dc field. The observation of multiple relaxation pathways clearly distinguishes 1 from the Cl and Br analogues.

A family of complexes with N-scorpionate-type and other N-donor ligands obtained in situ from pyrazole derivative and zerovalent cobalt. Physicochemical and cytotoxicity studies

In this paper we described one pot synthetic pathways which generated in situ three complexes which contain three different ligands: N,N,N-tris(3,5-dimethylpyrazolylmethyl)amine (L¹), urotropine (L²) and 3,5-dimethylpyrazole (L³).

A new family of [CuIILnIIIMV] heterotrimetallic complexes (Ln = La, Gd, Tb; M = Mo, W): model systems to probe exchange interactions and single-molecule magnet properties

Four 3d–4f–4(5)d heterotrimetallic complexes, [L²CuLn(H₂O)₅(μ-NC)M(CN)₇], were obtained from the association of the binuclear 3d–4f complexes and {M^V(CN)₈}³⁻ metalloligands.

Hybrid organic-inorganic chlorozincate and a molecular zinc complex involving the in situ formed imidazo[1,5-a]pyridinium cation: serendipitous oxidative cyclization, structures and photophysical properties

Two novel compounds, the organic-inorganic hybrid [L](2)[ZnCl(4)] (1) and the coordination complex LZnCl(3) (2), where L is the 2-methyl-3-(pyridin-2-yl)imidazo[1,5-a]pyridinium cation, were prepared using the oxidative condensation-cyclization of 2-pyridinecarbaldehyde and CH(3)NH(2)·HCl in methanol in the presence of Zn(2+) cations. The metal-free interaction of the organic components afforded the salt [L][Cl]·1.5H(2)O (3). The use of methylamine hydrochloride instead of its aqueous solution is believed to be responsible for the cyclocondensation with the formation of L instead of the expected Schiff base ligand. Compounds 1-3 have been obtained as single crystals and characterized by elemental analysis, IR, NMR spectroscopy, and single-crystal X-ray diffraction techniques. The structure of 1 is described as layers of cations and anions stacked along the c-axis, with the minimum ZnZn distance being 8.435 Å inside a layer. In the crystal lattice of 3, the cations are arranged in stacks propagating along the a-axis; the 1D H-bonding polymer built of chloride ions and water molecules runs parallel to a column of stacked cations. The organic cations in salts 1 and 3 show various patterns of π-π stacking. The discrete molecular structure of 2 shows coordination of a Zn atom to the N(pyridyl) atom, which enables one of the chloride atoms attached to the metal centre to interact with a π-system of the positively charged imidazolium ring. Numerous C-HCl contacts in a 1-3 are seen as space-filling van der Waals interactions of minor importance in determining crystal packing. The (1)H NMR studies suggest that the Zn-N coordination found in the solid-state structure of 2 is not retained in dmso, and 1, 2 and 3 are completely dissociated in solution. The emission spectra of 1 and 2 (λ(max) = 455 and 445 nm, respectively) exhibit red-shifts of fluorescence wavelength when compared to 3 and differ in the shapes and maxima of the emission as well as in relative fluorescence intensity.

Direct synthesis of a {Co₆(III)Fe₆(III)} dodecanuclear complex, revealing an unprecedented molecular structure type

A novel heterometallic Co6Fe6 Schiff base complex, possessing an unprecedented {M12(μ-X)22} branched structure (according to the search via the Cambridge Structural Database), has been prepared using the "direct synthesis" approach and characterized by single crystal X-ray diffraction and magnetometry.

A self-assembled octanuclear complex bearing the uncommon close-packed {Fe4Mn4(μ4-O)4(μ-O)4} molecular core

An Fe/Mn Schiff base complex with an unprecedented metal core type for a heterometallic compound, has been prepared by the one-pot direct synthesis method and magnetostructurally characterized.