Azide-Bridged One-Dimensional MnIII Polymers: Effects of Side Group of Schiff Base Ligands on Structure and Magnetism

Weakening the Interchain Interactions in One Dimensional Cobalt(II) Coordination Polymers by Preventing Intermolecular Hydrogen Bonding

The reaction of Co(NCS)₂ with N-methylaniline leads to the formation of [Co(NCS)₂(N-methylaniline)₂]_n (1), in which the cobalt(II) cations are octahedrally coordinated and linked into linear chains by pairs of thiocyanate anions. In contrast to [Co(NCS)₂(aniline)₂]_n (2) reported recently, in which the Co(NCS)₂ chains are linked by strong interchain N-H···S hydrogen bonding, such interactions are absent in 1. Computational studies reveal that the cobalt(II) ions in compound 1 show an easy-axis anisotropy that is lower than in 2, but with the direction of the easy axis being similar in both compounds. The high magnetic anisotropy is also confirmed by magnetic and FD-FT THz-EPR spectroscopy, which yield a consistent g_z value. These investigations prove that the intrachain interactions in 1 are slightly higher than in 2. Magnetic measurements reveal that the critical temperature for magnetic ordering in 1 is significantly lower than in 2, which indicates that the elimination of the hydrogen bonds leads to a weakening of the interchain interactions. This is finally proven by FD-FT THz-EPR experiments, which show that the interchain interaction energy in the N-methylaniline compound 1 is nine-fold smaller than in the aniline compound 2.

A Series of Manganese(III) Salen Complexes as a Result of Team-Based Inquiry in a Transnational Education Programme

The development of a team-based approach to research-led transnational practical chemistry teaching is described in which a team of five Chinese students on an articulated transnational degree programme, supported by a team of academic and technical staff, carried out a study examining the structural chemistry of a series of manganese(III) salen complexes. A series of four crystallographically characterized manganese(III) salen complexes with ancillary carboxylate ligands are reported here. The carboxylate coordination modes range from the bridging syn-anti μ² -κO : κO' mode observed in the predominant cyclohexanoate and isobutyrate species, to a capping terminal monodentate mode for the adamantanoate species, and an unusual mixture of bridging and terminal coordination modes observed in a second minor phase of the cyclohexanoate species. The variation on extended structures based on the weakly interacting aliphatic backbones may provide a useful basis for further structural studies.

Impact of the Schiff base ligand substituents on the solid state and solution properties of eleven iron(iii) complexes

A series of novel iron(iii)-Schiff base complexes have been prepared and structurally characterised. Their stereochemical, magnetic and redox properties were correlated with the molecular design of the corresponding N₃O₂-pentadentate Schiff base ligand.

Weak ferromagnetism derived from spin canting in an amido-bridged homochiral Mn(iii) 1-D coordination polymer

An amido-bridged homochiral one-dimensional (1D) Mn(iii) coordination polymer behaves as a weak ferromagnet arising from spin canting with a coercive field of 3.0 kOe.

Crystal structure of di-μ-acetato-di-acetatobis-(μ-6,6'-dimeth-oxy-2,2'-{[(propane-1,3-diylbis(aza-nylyl-idene)]bis-(methanylyl-idene)}diphenolato)tetra-zinc

The tetra-nuclear title complex, [Zn4(C19H20N2O4)2(CH3COO)4], is formed from two dinuclear motifs related by an inversion centre. The two crystallographically independent Zn(II) ions in the asymmetric unit are in different coordination environments. One is square-based pyramidal with one O atom of an acetate group occupying the axial position and two N and O atoms of one bmspd [H2bmspd = N,N'-bis-(3-meth-oxy-salicyl-idene)propyl-ene-1,3-di-amine] Schiff base ligand forming the basal plane. The other Zn(II) atom is six-coordinated by four O atoms of the bmspd ligand forming the equatoral plane and two O atoms of different acetate groups located in the axial positions. As a result, the two phenolic planes of the bicompartmental Schiff base ligand are distorted slightly. However, the planes of the two Schiff base ligands are parallel. In addition, the Zn-N and Zn-O bond lengths span the reasonable ranges 2.062 (2)-2.073 (2) and 1.9261 (15)-2.4356 (16) Å, respectively. The Zn⋯Zn distances separated by phenolic O atoms are 3.2466 (4) Å while the Zn⋯Zn distances bridged by acetate groups are 5.9835 (6) Å. The tetra-nuclear moieties are connected by van der Waals interactions, and form a chain along c axis.

Three Chiral Schiff-Base-Manganese(III)-Based Complexes: Synthesis, Structures and Magnetic Properties

Three chiral manganese(III) Schiff-base complexes [Mn(R,R-Salcy)(CH3OH)(N3)], [Mn(S,S-Salcy)(DMF)(N3)] (both monomers by X-structure determination) and the trinuclear complex (X-ray structure) {[Mn(R,R-Salcy)(H2O)]2[μ-Ni(CN)4]}·3CH3OH·H2O [Salcy = N,N′-(1,2-cyclohexanediylethylene)bis(salicylideneiminato)dianion)] have been synthesised. The trimeric complex shows weak antiferromagnetic interactions between the adjacent Mn(III) ions.

Two water-bridged cobalt(ii) chains with isomeric naphthoate spacers: from metamagnetic to single-chain magnetic behaviour

Two water-bridged cobalt(ii) chains with isomeric naphthoate spacers exhibit metamagnetic and SCM behaviours, arising from the dramatically different interchain stacking induced by naphthoate isomers.

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.

A family of ligand and anion dependent structurally diverse Cu(ii) Schiff-base complexes and their catalytic efficacy in an O-arylation reaction in ethanolic media

Catalytic O-arylation reactions have been studied by employing a variety of copper(ii) Schiff-base complexes under environmentally benign conditions.

Preparation, crystal structures and conformations of six complexes based on 1,4-bis(benzimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene

Six manganese(ii), cobalt(ii), copper(ii) and cadmium(ii) complexes based on dibenzimidazolyl ligands with the 1,2,4,5-tetramethylbenzene linker have been prepared and characterized.

Solvent-free synthesis, spectral correlations and antimicrobial activities of some aryl imines

A series of aryl imines have been synthesized by Fly-ash: H2SO4 catalyzed microwave assisted process under solvent-free conditions. The yields of the imines have been found to be more than 87%. The purity of all imines has been checked using their physical constants and spectral data as published earlier in literature. The UV λmaxCN(nm), infrared νCN(cm(-1)), NMR δ(ppm) of CH and CN spectral data have been correlated with Hammett substituent constants and F and R parameters using single and multi-linear regression analysis. From the results of statistical analysis, the effect of substituents on the above spectral data has been studied. The antimicrobial activities of All synthesised imines have been studied using Bauer-Kirby method.

Mononuclear and dinuclear manganese compounds stabilized by supramolecular interactions

New manganese compounds [Mn(HphpzMe)(2)(H(2)phpzMe)(HCO(2))] (1), [Mn(2)(phpzMe)(2)(HphpzMe)(2)(OCH(3))]·2CH(3)OH (2), Na{[Mn(HphpzPh)(phpzPh)(MeOH)(2)](2)}(HCO(2)) (3), [Mn(HphpzPh)(2)(EtOH)(2)]ClO(4)·2EtOH (4) and [Mn(HphpzPh)(2)N(3)] (5) were synthesized and characterized with various techniques. 1, 4 and 5 are mononuclear manganese(III) compounds, 2 is a mixed-valence dinuclear manganese(III/IV) compound, and 3 is a trinuclear compound containing two manganese(III) ions and a sodium(I) ion. A remarkable feature is the spontaneous formation of the formate ion as a result of the methanol or methoxide oxidation in compounds 1 and 3. Using ethanol precludes the formation of the formate and compound 4 is obtained. The molecular structure of all compounds is stabilized by supramolecular interactions, including strong hydrogen bonding and π-π interactions.