Coordination of 1,4-disubstituted 1,2,3-triazoles L 1 and L 2 with [(p-cymene)­RuCl2]2 followed by dehydrochlorination in the presence of a base resulted in the formation of complexes 1 and 2, respectively. Both were tested for the transfer hydrogenation of aldehydes and ketones in air using ecologically benign and cheap ethanol as the hydrogen source in the presence of a catalytic amount of a base. Air-stable complex 1 was proved to be an active catalyst for the transfer hydrogenation of a wide variety of aromatic and aliphatic aldehydes and ketones bearing various functionalities. Catalyst 1 was also effective for the transfer hydrogenation of carbonyls using the simplest primary alcohol, methanol, under aerobic conditions. Under the present catalytic protocol, labile or reducible functionalities such as nitro, cyano, and ester groups were tolerated. Good selectivity was also observed for acyclic α,β-unsaturated carbonyls. However, this catalytic protocol was not selective for 2-cyclohexen-1-one as both alkene and keto moieties were reduced. The transfer hydrogenations are believed to proceed via a ruthenium-hydride intermediate. Finally, transfer hydrogenation of acetophenone using isopropanol as a commonly used hydrogen source was also performed and the sustainable and green credentials of these catalytic protocols utilizing methanol, ethanol, and isopropanol were compared with the help of the CHEM21 green metrics toolkit.

Some mononuclear and dinuclear Ni(ii) complexes with tetradentate Schiff base ligands exhibit zero-field splitting and ferromagnetic coupling, respectively.

In this article, the synthesis and X-ray crystal structures of two cis/trans isomers of valence tautomeric (VT) cobalt dioxolene compounds are reported. The cis isomer (1) was isolated from the polar protic methanol solvent as a kinetic product, whereas the less polar nonprotic solvent acetone yielded the trans isomer (2). It should be noted that, although some coordination polymers involving cobalt bis(dioxolene) with the cis disposition are known for bridging ancillary ligands, such an arrangement is unprecedented for mononuclear compounds. A careful study of intermocular interactions revealed that the methanol solvent does not have much influence on the crystal growth in 1, whereas acetone forms strong halogen-bonding interactions that are crucial in the solid-state architecture of 2. This behavior can likely be used in crystal engineering to design new organic-inorganic hybrid materials. The energy difference between the two isomers was examined using DFT calculations, confirming that the trans form is in the thermodynamic state whereas the cis isomer is a kinetic product that can be converted into the trans isomer with time. Finally, both isomers exhibit solvent loss at elevated temperatures that is accompanied by a change in magnetic properties, associated with an irreversible valence tautomerism. Our results highlight the crucial role of the solvents for the isolation of cis/trans isomers in cobalt dioxolene chemistry, as well as the distinguishing effects of intermolecular forces and the solid-state packing on VT behavior.

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Two butterfly-shaped Dy4 and Zn2Dy2 complexes displaying slow relaxation of magnetization have been synthesized from a new methyl substituted o-vanillin based ligand, enlarging the scope for finding better SMMs.

Six dimetallic lanthanide complexes, [Ln2(L′)(acac)4] (1Dy–3Gd) (Ln = Dy (1Dy), Tb (2Tb) and Gd (3Gd)) and [Ln2(L′)(tfac)4] (4Dy–6Gd) (Ln = Dy (4Dy), Tb (5Tb) and Gd (6Gd)) (H2L′ = 1,9-dichloro-3,7,11,15-tetraaza-1,9(1,3)-dibenzenacyclohexadecaphane-2,10-diene-1,9-diol),...

Three new angular trinuclear Zn2Dy complexes, [Dy{Zn(L)Cl}2(H2O)2]Cl∙3H2O (1), [Dy{Zn(L)Br}2(H2O)2](NO3)∙4H2O (2) and [Dy{Zn(L)I}2(H2O)2](NO3)∙4H2O (3), derived from a methyl substituted o-vanillin based Schiff base ligand, N,N'-bis(3-methoxy-5-methylsalicylidene)-1,2-phenylenediamine (H2L), have been synthesized and magneto-structurally...

The need of sustainable development in modern era has driven the transformation of biomass for the production of fine chemicals into a strong trend of research. The aerobic oxidation of...