Naveen Satrawala

In this report, the catalytic potential of chalcogen-stabilized iron carbonyl clusters [Fe₃E₂(CO)₉ (E = S, Se, Te)] for the photolytic hydration of alkynes has been explored. The iron chalcogenide clusters bring excellent transformations of terminal and internal alkynes to their respective keto products in just 25 min photolysis at −5 °C in inert free and aqueous conditions. After the completion of the reaction, the product can be extracted from organic solvent, and due to the lower solubility of the catalyst in water, it can also be isolated and further reused several times prior to any activation. The catalyst was also found to be active in thermal conditions and bring about the desired transformations with average to good catalytic efficiency. Moreover, during the thermal reaction, the catalyst decomposed and formed the nanoparticles of iron selenides, which worked as a single-source precursor for FeSe nanomaterials. The presented photolysis methodology was found to be most feasible, economical, instantly produce the desired product, and work for a wide range of internal and terminal alkynes; hence, all these features made this method superior to the other reported ones. This report also serves as the first catalytic report of chalcogen-stabilized iron carbonyl clusters for alkyne hydrations.

A new benzimidazolium salt, 1‐[benzylaminocarbonylmethyl]‐3‐(2‐phenylsulfanylethyl)‐1H‐benzimidazolium chloride (L), which is a precursor of a novel thioether‐functionalized NHC, has been synthesized by subjecting 1H‐benzimidazole to a sequence of reactions with 1,2‐dichloroethane, sodium thiophenolate, and N‐benzyl‐2‐chloroacetamide, successively. The moisture/air‐insensitive complex [Pd(L–HCl)Cl₂] (1) was prepared by the reaction of L with PdCl₂. The molecular structure of 1, established by X‐ray crystallography, revealed a square‐planar geometry around Pd. Complex 1 was screened for Suzuki–Miyaura coupling reactions of various aryl/heteroaryl bromides (yields of up to 94 % in 2 h) in water at room temperature. Furthermore, complex 1 was immobilized onto the surface of aminopropyl‐functionalized silica‐coated magnetite nanoparticles [NPs, Fe₃O₄@SiO₂‐(CH₂)₃‐NH₂] by a stepwise modification strategy to develop the heterogeneous magnetically retrievable catalyst Fe₃O₄@SiO₂‐1′, in which the amide functionality present in the side‐arm of the NHC within the NHC–Pd^II complex serves as linker. This magnetic nanosupport, bearing palladium complexes incorporating a novel thioether‐based NHC ligand that functions in aqueous aerobic medium and can be easily separated, renders Fe₃O₄@SiO₂‐1′ a most desirable catalyst for the Suzuki–Miyaura coupling reaction. It was also observed that the catalyst was effective for up to seven cycles and was easily separated from the reaction medium by the use of an external magnet, further increasing its appeal.