Diruthenium(II,III) tetracarboxylates catalyzed H2O2 oxygenation of organic sulfides

Synthesis, crystal structures and fluorescence properties of two 1D Zn(II) homologous coordination polymers

A pair of zinc(II)-based one-dimensional (1D) homologous coordination polymers, [Zn(Hdba)2(bib)] n (1) and [Zn(Hdba)2(bmib)] n (2), where H2dba = 3-hydroxybenzoic acid, bib = 1,4-bis(1-imidazolyl)benzene, and bmib = 1,4-bis(2-methyl-1H-imidazol-1-yl)benzene were hydrothermally synthesized and characterized through infrared spectroscopy (IR), elemental and thermal analysis (EA), powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD) analyses. The results revealed that 1 and 2 have the same zigzag infinite chain framework through the partially deprotonated Hdba– monodentate linkage and with μ 2-bib bridging the Zn(II) atoms in 1, and with μ 2-bmib bridges for the Zn(II) atoms in 2. For both 1 and 2, each zinc atom has a slightly twisted tetrahedral configuration with a N2O2 donor set. These chains of 1 and 2 are further connected into three-dimensional (3D) supramolecular structures through O–H···O, C–H···O hydrogen bonds and π···π, C–H···π stacking interactions for 1, and O–H···O, C–H···O hydrogen bonds for 2. Topologically, the 3D hydrogen-bonded organic framework or the 2D π-stacking structure of 1 can be simplified as a 4-connected dia Diamond type with a Schläfli symbol {66}, or as a 4-connected sql type with a Schläfli symbol {44·62} and a Shubnikov tetragonal plane net. The thermal stability and the solid-state fluorescence properties of 1 and 2 were investigated.

Electronic Structure of Ru26+ Complexes with Electron-Rich Anilinopyridinate Ligands

Diruthenium paddlewheel complexes supported by electron-rich anilinopyridinate (Xap) ligands were synthesized in the course of the first in-depth structural and spectroscopic interrogation of monocationic [Ru₂(Xap)₄Cl]⁺ species in the Ru₂⁶⁺ oxidation state. Despite paramagnetism of the compounds, ¹H NMR spectroscopy proved highly informative for determining the isomerism of the Ru₂⁵⁺ and Ru₂⁶⁺ compounds. While most compounds are found to have the polar (4,0) geometry, with all four Xap ligands in the same orientation, some synthetic procedures resulted in a mixture of (4,0) and (3,1) isomers, most notably in the case of the parent compound Ru₂(ap)₄Cl. The isomerism of this compound has been overlooked in previous reports. Electrochemical studies demonstrate that oxidation potentials can be tuned by the installation of electron donating groups to the ligands, increasing accessibility of the Ru₂⁶⁺ oxidation state. The resulting Ru₂⁶⁺ monocations were found to have the expected (π*)² ground state, and an in-depth study of the electronic transitions by Vis/NIR absorption and MCD spectroscopies with the aid of TD-DFT allowed for the assignment of the electronic spectra. The empty δ* orbital is the major acceptor orbital for the most prominent electronic transitions. Both Ru₂⁵⁺ and Ru₂⁶⁺ compounds were studied by Ru K-edge X-ray absorption spectroscopy; however, the rising edge energy is insensitive to redox changes in the compounds due to the broad line shape observed for 4d transition metal K-edges. DFT calculations indicate the presence of ligand orbitals at the frontier level, suggesting that further oxidation beyond Ru₂⁶⁺ will be ligand-centered rather than metal-centered.

Steric, Activation Method and Solvent Effects on the Structure of Paddlewheel Diruthenium Complexes

Conventional heating and solvothermal synthetic methods (with or without microwave activation) have been used to study the reaction of o-, m- and p-methoxybenzoic acid with [Ru2Cl(μ-O2CMe)4]. The tetrasubstituted series [Ru2Cl(µ-O2CC6H4-R)4], with R = o-OMe, m-OMe and p-OMe, has been prepared by the three procedures. Depending on the synthetic method and the experimental conditions, three compounds have been isolated (1a, 1b, 1c) with the o-methoxybenzoate ligand. However, with the m- and p-methoxybenzoate ligands, only the complexes 2 and 3 have been obtained, respectively. Compound 1a, with stoichiometry [Ru2Cl(µ-O2CC6H4-o-OMe)4]n, shows a polymeric structure with the chloride ions bridging the diruthenium units to form linear chains. Compounds 2 and 3, with the same stoichiometry, predictably form zig-zag chains in accordance with their insolubility and their magnetic measurements. Compound 1b, [Ru2Cl(µ-O2CC6H4-o-OMe)4(EtOH)], is a discrete molecular species with a chloride ion and one ethanol molecule occupying the axial positions of the dimetallic unit. Compound 1c is a cation-anion complex, [Ru2(µ-O2CC6H4-o-OMe)4(MeOH)2][Ru2Cl2(µ-O2CC6H4-o-OMe)4]. The cationic complex has two solvent molecules at the axial positions whereas the anionic complex has two chloride ligands at these positions. Complexes have been characterized by elemental analyses, mass spectrometry and IR and UV-vis-NIR spectroscopies. A magnetic study of complexes 1a, 1b, 2 and 3 have also been carried out. The crystal structure of compounds 1b and 1c have been solved by single X-ray crystal methods.

catena-Poly[[tetrakis(μ-3,4,5-trimethoxybenzoato-κ2 O:O′)diruthenium(II,III)(Ru—Ru)]-μ-chlorido] with an unknown solvent

[Ru2Cl{μ-O2CC6H2-3,4,5-(OMe)3}4] n was prepared by the reaction of [Ru2Cl(μ-O2CCH3] n with 3,4,5-trimethoxybenzoic acid. The complex shows a paddlewheel structure with pairs of Ru atoms bridged by four carboxylate ligands. The axial positions are occupied by shared chloride ions giving zigzag chains. These chains are disposed parallel to each other to give a three-dimensional arrangement packed only by van der Waals forces. The final refinement shows high values of residual non-modelled electronic density. Therefore, the SQUEEZE utility [Spek (2015). Acta Cryst. C71, 9–18] was used to remove its contribution to the overal intensity data. The electron density modelled by SQUEEZE is consistent with around eight water molecules per unit cell.

Crystal structure of bis-(tri-ethano-lamine-κ(3) N,O,O')nickel(II) bis-(3-hy-droxy-benzoate) tetra-hydrate

The reaction of 3-hy-droxy-benzoic (m-hy-droxy-benzoic) acid (MHBA), tri-ethano-lamine (TEA) and Ni(NO3)2 in aqueous solution led to formation of the hydrated title salt, [Ni(C6H15NO3)2](C7H5O3)·4H2O. In the complex cation, the Ni(2+) ion is located on an inversion centre. Two symmetry-related TEA ligands occupy all coordination sites in an N,O,O'-tridentate coordination, leading to a slightly distorted NiN2O4 octa-hedron. Two ethanol groups of each TEA ligand form two five-membered chelate rings around Ni(2+), while the third ethanol group does not coordinate to the metal atom. Two MHBA(-) anions in the benzoate form are situated in the outer coordination sphere for charge compensation. An intricate network of hydrogen bonds between the free and coordinating hy-droxy groups of the TEA ligands, the O atoms of the MHBA(-) anions and the water mol-ecules leads to the formation of a two-dimensional structure extending parallel to (010).