A simple and efficient tetradentate Schiff base derived palladium complex for Suzuki–Miyaura reaction in water

Overview on magnetically recyclable ferrite nanoparticles: synthesis and their applications in coupling and multicomponent reactions

Nanocatalysis is an emerging area of research that has attracted much attention over the past few years. It provides the advantages of both homogeneous as well as heterogeneous catalysis in terms of activity, selectivity, efficiency and reusability. Magnetically recoverable nanocatalysts provide a larger surface area for the chemical transformations where the organic groups can be anchored and lead to decrease in the reaction time, increase in the reaction output and improve the atom economy of the chemical reactions. Moreover, magnetic nanocatalysts provide a greener approach towards the chemical transformations and are easily recoverable by the aid of an external magnet for their reusability. This review aims to give an insight into the important work done in the field of magnetically recoverable nanocatalysts and their applications in carbon-carbon and carbon-heteroatom bond formation.

Selective Formation, Reactivity, Redox and Magnetic Properties of MnIII and FeIII Dinuclear Complexes with Shortened Salen-Type Schiff Base Ligands

The reactivity of the shortened salen-type ligands H₃salmp, H₂salmen and H₂sal(p-X)ben with variable para-substituent on the central aromatic ring (X = tBu, Me, H, F, Cl, CF₃, NO₂) towards the trivalent metal ions manganese(III) and iron(III) is presented. The selective formation of the dinuclear complexes [M₂(μ-salmp)₂], M = Mn (1a), Fe (2a), [M₂(μ-salmen)₂(μ-OR)₂)], R = Et, Me, H and M = Mn (3a–c) or Fe (4a–c), and (M₂(μ-sal[p-X]ben)₂(μ-OMe)₂), X = tBu, Me, H, F, Cl, CF₃, NO₂ and M = Mn (5a–g) or Fe (6a–g), could be identified by reaction of the Schiff bases with metal salts and the base NEt₃, and their characterization through elemental analysis, infrared spectroscopy, mass spectrometry and single-crystal X-ray diffraction of 2a·2AcOEt, 2a·2CH₃CN and 3c·2DMF was performed. In the case of iron(III) and H₃salmp, when using NaOH as a base instead of NEt₃, the dinuclear complexes [Fe₂(μ-salmp)(μ-OR)(salim)₂], R = Me, H (2b,c) could be isolated and spectroscopically characterized, including the crystal structure of 2b·1.5H₂O, which showed that rupture of one salmp³⁻ to two coordinated salim⁻ ligands and release of one salH molecule occurred. The same hydrolytic tendency could be identified with sal(p-X)ben ligands in the case of iron(III) also by using NEt₃ or upon standing in solution, while manganese(III) did not promote such a C–N bond breakage. Cyclic voltammetry studies were performed for 3b, 4b, 5a and 6a, revealing that the iron(III) complexes can be irreversibly reduced to the mixed-valence Fe^IIFe^III and Fe^II₂ dinuclear species, while the manganese(III) derivatives can be reversibly oxidized to either the mixed-valence Mn^IIIMn^IV or to the Mn^IV₂ dinuclear species. The super-exchange interaction between the metal centers, mediated by the bridging ligands, resulted in being antiferromagnetic (AFM) for the selected dinuclear compounds 3b, 4b, 5a, 5e,5f, 6a and 6e. The coupling constants J (–2JŜ₁·Ŝ₂ formalism) had values around −13 cm⁻¹ for manganese(III) compounds, among the largest AFM coupling constants reported so far for dinuclear Mn^III₂ derivatives, while values between −3 and −10 cm⁻¹ were obtained for iron(III) compounds.

Tuning of Catalytic Property Controlled by the Molecular Dimension of Palladium-Schiff Base Complexes Encapsulated in Zeolite Y

Planar palladium-Schiff base complexes are synthesized, maintaining the order of their molecular dimensions as PdL1 < PdL2 < PdL3 < PdL4 < PdL5 in free state, as well as encapsulated in zeolite Y, where L1: N,N'-bis(salicylidene)ethylenediamine and L2, L3, L4, and L5 are derivatives of L1. All encapsulated complexes have shown better catalytic activity for the sulfoxidation of methyl phenyl sulfide in comparison to their homogeneous counter parts. These hybrid systems are characterized with the help of different characterization techniques such as X-ray diffraction analysis, scanning electron microscopy-energy-dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, Fourier transform infrared, and UV-visible spectroscopy; all of these studies have suggested that the largest complex deviates by the maximum from its free-state properties, and a radical change in the reactivity of the complex is observed.

Starch assisted palladium(0) nanoparticles as in situ generated catalysts for room temperature Suzuki–Miyaura reactions in water

The in situ generated PdNPs show excellent catalytic activity in Suzuki–Miyaura cross coupling reaction of electronically diversified arylbromides and arylboronic acids in water at room temperature with low catalyst loading.

A palladium salen complex: an efficient catalyst for the Sonogashira reaction at room temperature

A tetradentate Schiff base derived palladium complex works as an efficient catalyst for the room temperature Sonogashira reaction.

A facile approach for the synthesis of novel 1-oxa- and 1-aza-flavonyl-4-methyl-1H-benzo[d][1,3]oxazin-2(4H)-ones by microwave enhanced Suzuki–Miyaura coupling using bidentate chromen-4-one-based Pd(ii)–diimine complex as catalyst

A facile access to novel 1-oxa- and 1-aza-flavonyl-4-methyl-1H-benzo[d][1,3]oxazin-2(4H)-ones using microwave assisted Suzuki coupling of bromo flavones with boronic acids using a novel catalytic system (C) under aerobic condition is reported.

Palladium-Schiff-base-silica framework as a robust and recyclable catalyst for Suzuki–Miyaura cross-coupling in aqueous media

A novel Pd@imine-SiO₂ catalyst was prepared and found to exhibit excellent catalytic activity in a Suzuki-Miyaura cross-coupling reaction under aqueous media at room temperature.

Pd(OAc)2 and (DHQD)2PHAL as a simple, efficient and recyclable/reusable catalyst system for Suzuki–Miyaura cross-coupling reactions in H2O at room temperature

Suzuki–Miyaura cross-coupling reaction catalyzed by Pd(OAc)₂–(DHQD)₂PHAL is a very simple, mild, efficient and recyclable/reusable protocol for the synthesis of biaryls/heterobiaryls in neat H₂O at room temperature.

CH⋯Pd interactions: one dimensional heteropolynuclear complexes

Three cyanide complexes, [Cu(hepH)2Pd(μ-CN)2(CN)2]n (1), [Zn(hepH)2Pd(μ-CN)2(CN)2]n (2) and [Cd(hepH)2Pd(μ-CN)2(CN)2]n (3) (2-pyridineethanol abbreviated to hepH), have been synthesized and characterized by various techniques (elemental analysis, FT-IR and Raman spectroscopy, thermal analysis and single crystal X-ray diffraction). FT-IR spectroscopy pointed out the existence of terminal and bridged cyanide ligands in the complexes. The crystallographic analyses reveal that complexes 1 and 2 crystallize in the triclinic system, space group P-1 and complex 3 crystallizes in the monoclinic system, space group P2₁/n. The palladium atom is coordinated with cyanide-carbon atoms in a square-planar arrangement and the metal(II) atoms are six-coordinated with two cyanide nitrogen, two hepH nitrogen and two hepH oxygen atoms, in a distorted octahedral arrangement. In all the complexes adjacent chains are connected by CH⋯Pd, π⋯π and OH⋯N hydrogen bonding interactions to form two- and three-dimensional networks. When it comes to thermal analysis, the complexes followed usual decomposition mechanism in which neutral ligands (hepH) are released first, and then cyanide ligands are decomposed. The final decomposition products are found to be the corresponding metal oxides.