Manganese(II) complexes with croconate and 2-(2-pyridyl)imidazole ligands: Syntheses, X-ray structures and magnetic properties

A "Pretender" Croconate-Bridged Macrocyclic Tetraruthenium Complex: Sizable Redox Potential Splittings despite Electronically Insulated Divinylphenylene Diruthenium Entities

Careful optimization of the reaction conditions provided access to the particularly small tetraruthenium macrocycle ²Ru₂Ph-Croc, which is composed out of two redox-active divinylphenylene-bridged diruthenium entities {Ru}-1,4-CH=CH-C₆H₄-CH=CH-{Ru} (Ru₂Ph; {Ru} = Ru(CO)Cl(PⁱPr₃)₂) and two likewise redox-active and potentially non-innocent croconate linkers. According to single X-ray diffraction analysis, the central cavity of ²Ru₂Ph-Croc is shielded by the bulky PⁱPr₃ ligands, which come into close contact. Cyclic voltammetry revealed two pairs of split anodic waves in the weakly ion pairing CH₂Cl₂/NBu₄BAr^F₂₄ (BAr^F₂₄ = [B{C₆H₃(CF₃)₂-3,5}₄]⁻ electrolyte, while the third and fourth waves fall together in CH₂Cl₂/NBu₄PF₆. The various oxidized forms were electrogenerated and scrutinized by IR and UV/Vis/NIR spectroscopy. This allowed us to assign the individual oxidations to the metal-organic Ru₂Ph entities within ²Ru₂Ph-Croc, while the croconate ligands remain largely uninvolved. The lack of specific NIR bands that could be assigned to intervalence charge transfer (IVCT) in the mono- and trications indicates that these mixed-valent species are strictly charge-localized. ²Ru₂Ph-Croc is hence an exemplary case, where stepwise IR band shifts and quite sizable redox splittings between consecutive one-electron oxidations would, on first sight, point to electronic coupling, but are exclusively due to electrostatic and inductive effects. This makes ²Ru₂Ph-Croc a true “pretender”.

Design of 3d–4f molecular squares through the [Fe{(HB(pz)3)}(CN)3]− metalloligand

A new series of cyanido-bridged {FeIII2LnIII2} heterobimetallic molecular squares [Ln = La (1), Gd (2), Tb (3) and Dy (4)] has been prepared and magneto-structurally investigated.

Croconato-bridged copper(ii) complexes: synthesis, structure and magnetic characterization

Three croconato-bridged Cu(ii) complexes were synthesized and structurally and magnetically characterized.

(Ethylenediamine-κ2N,N)bis[2-(pyridin-2-yl-κN)-1,3-imidazol-1-ido-κN1]cobalt(III) nitrate monohydrate

In the title compound, [Co(C₈H₆N₃)₂(C₂H₈N₂)]NO₃·H₂O, the Co^III ion is coordinated by four N atoms from two 2-(pyridin-2-yl)-1,3-imidazol-1-ide ligands and two N atoms of ethyl­enediamine in a distorted octa­hedral geometry. In the crystal, classical N—H⋯N(O) and O—H⋯N(O) hydrogen bonds connect all the isolated components together to yield a three-dimensional structure.

Synthesis, characterization and spectroscopic studies of 2,2″-bipyridyl complexes of metal benzenesulfonates

The new transition metal benzenesulfonate (bs) complexes of 2,2″-bipyridyl (bpy) have been synthesized and characterized by elemental analyses, magnetic moments, UV-Vis, IR, thermal analysis techniques. The bs anion does not coordinate to the metal ions and is present as the counter-ion in the Co(II) (2), Ni(II) (3) and Cu(II) (4) complexes, but coordinates to the Mn(II) ion as a monodentate ligand. The Mn(II) complex (1) crystallizes in the orthorhombic crystal system with Pbca space group. The complex (1) is the first crystallographically characterized Mn(II) benzenesulfanato complex in which the bs anion is coordinated to metal ion. The manganese centre has a significantly distorted octahedral coordination by two bpy and bs ligands. bs molecules are joined by O7—H7A...O2 and O7—H7B...O3 hydrogen bonds, forming a centrosymmetric dimers which are linked by π–π interactions. All complexes exhibit similar decomposition characteristics. Magnetic susceptibility measurement shows that complex 2 has orbital interaction.