Tetranuclear copper(II) complex of 2-hydroxy-N,N′-bis[1-(2-hydroxyphenyl)ethylidene]propane-1,3-diamine

In the title Schiff base tetra­nuclear copper(II) complex, two discrete environments are present in the structure: CuNO₄ and CuNO₃. Two copper(II) cations are situated in distorted square-pyramidal environment, while two copper(II) cations are located in a slightly square-planar geometry. One bridging acetate group acting in an η¹:η¹-μ₂-mode connects two copper(II) ions, while another bridging acetate group connects three copper(II) ions in an η¹:-η²–μ₃-mode.

The title mol­ecular structure, namely, (μ₃-acetato)(μ₂-acetato)­bis­(μ₃-1,3-bis­{[1-(2-oxidophen­yl)ethyl­idene]amino}­propan-2-olato)tetra­copper(II) monohydrate, [Cu₄(C₁₉H₁₉N₂O₃)₂(CH₃CO₂)₂]·H₂O, corresponds to a non-symmetric tetra­nuclear copper complex. The complex exhibits one ligand mol­ecule that connects two copper Cu^II metal centres via its ethano­lato oxygen anion acting in a μ₂-mode and one ligand mol­ecule that connects three copper Cu^II metal centres via its ethano­lato oxygen anion acting in a μ₃-mode. One bridging acetate group acting in an η¹:η¹-μ₂-mode connects two copper(II) ions while another bridging acetate group connects three copper(II) ions in an η¹:-η²-μ₃-mode. A chair-like Cu₃O₃ structure is generated in which the two CuO₄N units are connected by one μ₂-O ethano­late oxygen atom. These two units are connected respectively to the CuO₃N unit via one μ₃-O ethano­late oxygen atom and one μ₂-O atom from an acetate group. The μ₃-O atom also connects one of the CuO₄N units and the CuO₃N unit to another CuO₃N unit, which is out of the chair-like structure. Each of the two penta­coordinated Cu^II cations has a distorted NO₄ square-pyramidal environment. The geometry of each of the two CuNO₃ units is best described as a slightly square-planar environment. A series of intra­molecular O—H⋯O hydrogen bonds is observed. In the crystal, the units are connected by inter­molecular C—H⋯O and O—H⋯O hydrogen bonds, thus forming sheets parallel to the ac plane

Templated synthesis of Ni(ii) complexes of unsymmetrical Schiff base ligands derived from 1,3-diamino-2-propanol: structural diversity and magnetic properties

A Ferromagnetically coupled tetranuclear, an antiferromagnetically coupled hexanuclear and a mononuclear Ni(II) complex of new unsymmetrical Schiff base ligands derived from 1,3-diamino-2-propanol have been obtained with a slight change in the carbonyl compounds.

Hexanuclear copper(II) complex of 2-hy-droxy-N,N'-bis-[1-(2-hy-droxy-phen-yl)ethyl-idene]propane-1,3-di-amine incorporating an open-cubane core

The title mol-ecular structure, namely, di-aqua-tris-(μ3-1,3-bis-{[1-(2-oxidophen-yl)ethyl-idene]amino}-propan-2-olato)-μ3-hydroxido-dinitrato-hexa-copper(II) ethanol tris-olvate, [Cu6(C19H19N2O3)3(NO3)2(OH)(H2O)2]·3C2H5OH, corres-ponds to a non-symmetric hexa-nuclear copper complex. The complex exhibits one core in which three CuII metal centres are mutually inter-connected, two by two, via three phenolato oxygen anions acting in a μ2-mode. These three copper cations are inter-connected in a μ3-mode by one hydroxyl group. An open-cube structure is generated in which each of the CuII cations of the three CuO4N units is connected by two μ2-O anions from phenolate groups and one μ3-O atom from a hy-droxy anion. Each of the three penta-coordinated CuII cations situated in the open-cube unit has a distorted NO4 square-pyramidal environment. Each of these three CuII centres is inter-connected with another CuII cation via one enolate O atom in μ2-mode, yielding one CuNO4 unit and two CuNO3 units. The penta-coordinated CuII atom has a distorted square-pyramidal environment while the two tetra-coordinated copper(II) cations are situated in a square-planar environment. A series of intra-molecular O-H⋯O hydrogen bonds are observed. In the crystal, the units are connected two by two by inter-molecular C-H⋯O and O-H⋯O hydrogen bonds, thus forming sheets parallel to the ac plane.

Insight into non-covalent interactions in two triamine-based mononuclear iron(iii) Schiff base complexes with special emphasis on the formation of Br⋯π halogen bonding

The nature and characteristics of noncovalent interactions that play important roles in the crystal packing of two iron(iii) complexes have been discussed.

Facile synthesis of a new Cu(ii) complex with an unsymmetrical ligand and its use as an O3 donor metalloligand in the synthesis of Cu(ii)-Mn(ii) complexes: structures, magnetic properties, and catalytic oxidase activities

A new, facile Cu(ii) template method has been employed for the unsymmetrical dicondensation of 1,2-ethylenediamine with salicylaldehyde and o-vanillin. The mononuclear complex, [CuL] (1), thus obtained, has been used as an O₃ donor metalloligand for the synthesis of four new Cu(ii)-Mn(ii) complexes, [(CuL)MnCl₂] (2), [(CuL)Mn(NO₃)₂(CH₃OH)]_n (3), {[(CuL)Mn(benz)(H₂O)]₂·(CuL)₂(ClO₄)₂} (4) and [(CuL)Mn(benz)Cl]₂ (5) (where benz = benzoate). Single-crystal structural analyses reveal that 2 is a dinuclear complex while complex 3 is polymeric with a repeating dinuclear [(CuL)Mn(NO₃)₂(CH₃OH)] unit, linked via the nitrate ion. Both 4 and 5 are discrete tetranuclear complexes, where the dinuclear units [(CuL)Mn(benz)(H₂O)] and [(CuL)Mn(benz)Cl] are connected by double benzoate and double chloride bridges, respectively. In complex 4, two monomeric [CuL] units are cocrystallized with the tetranuclear complex. An important difference in the structure of 4 from the other three complexes is that one solvent water molecule is coordinated to each Mn(ii) ion, which makes complex 4 catalytically very active towards mimicking catecholase and phenoxazinone synthase-like oxidation reactions. The turnover numbers (k_cat) for the aerial oxidation of 3,5-di-tert-butylcatechol and o-aminophenol are 399 h^-1 and 230 h^-1, respectively. The evidence of the intermediate species in the mass spectra indicates possible heterometallic cooperation where the Mn(ii) center helps in substrate binding and Cu(ii) participates in the oxidation reactions with molecular oxygen. Cyclic voltammetry measurements suggest the reduction of Cu(ii) to Cu(i) during the catalytic process. Temperature-dependent dc molar magnetic susceptibility measurements reveal that complexes 2-5 are antiferromagnetically coupled with the exchange coupling constants (J) of J = -13.5 cm^-1 and J = -13.5 cm^-1 for 2 and 3, respectively, J₁ = -12.6 cm^-1 and J₂ = -1.20 cm^-1 for complex 4 and J₁ = -13.24 cm^-1 and J₂ = 0.36 cm^-1 for complex 5 as is expected from the Cu-O-Mn bridging angles.

Synthesis, characterization, self-assembly and non-ohmic Schottky barrier diode behaviors of two iron(iii) based semiconductors with theoretical insight

Schottky barrier diodes have been fabricated using two iron(iii) Schiff base complexes. The total and partial DOS values have been calculated using DFT to calculate the band gaps in these complexes.

A theoretical insight into non-covalent supramolecular interactions in the solid state structures of two octahedral iron(iii) complexes

The nature and characteristics of the C–H⋯π interactions that play an important role in crystal packing of two iron(iii) complexes have been discussed. The DFT calculations have been conducted to determine the interaction energies in these complexes.

Solvatomorphism and Electronic Communication in FeIII N,N-Bis(salicylidene)-1,3-propanediamine Dimers

The reaction of H2salpn (H2salpn = N,N′-bis(salicylidene)-1,3-propanediamine) with Fe(ClO4)3 in a ratio of 1 : 1 and 3 : 2, leads to dark red crystals of the solvatomorphs [(salpn)Fe(μ2-salpn)Fe(salpn)]·0.5MeOH (1) and [(salpn)Fe(μ2-salpn)Fe(salpn)]·MeOH (2), respectively. X-Ray crystallographic studies reveal a slightly distorted octahedral geometry and meridional configuration of the N and O donor atoms with one of the salpn ligands acting as a bridge between the two FeIII atoms to create a dimer. The Fe–N/O bond distances for both dimers indicate that the Fe centres are high spin. Supramolecular dimeric pairs are formed in both structures from C–H···π and/or C–H···O interactions. However, the degree of solvation significantly impacts the arrangements of these dimeric pairs with tightly packed 1D chains in 2 and more loosely packed chains in 1. In addition, electrochemical studies reveal weak communication between the two Fe atoms despite the large distance between them and the lack of conjugation across the bridge.

A combined experimental and computational study of supramolecular assemblies in ternary copper(ii) complexes with a tetradentate N4donor Schiff base and halides

Three new copper(ii) Schiff base complexes have been prepared and characterized. DFT calculations were employed to estimate the contribution of different non-covalent interactions in the extended supra-molecular networks.