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Herein, we have reported a new series of NNS‐donor ligands coordinated Ni(II) complexes and utilized them as catalytic activator to synthesize N‐alkylated amines and 1,2‐disubstituted benzimidazoles. The reaction of thiophenol/4‐chlorothiophenol/4‐methylthiophenol/4‐methoxythiophenol with 2‐bromo‐N‐quinolin‐8‐yl‐acetamide in presence of sodium hydroxide in ethanol at 80 °C gave [C9H6N‐NH−C(O)−CH2‐S−Ar] [Ar=C6H5 (L1); C6H4Cl‐4 (L2); C6H4Me‐4 (L3) and C6H4‐OMe‐4 (L4)], respectively. The corresponding reaction of L1‐L4 with Ni(OAc)2 in methanol at 80 °C for 3 hours resulted in octahedral nickel complexes [(L1‐H)2Ni] (C1), [(L2‐H)2Ni] (C2), [(L3‐H)2Ni] (C3), and [(L4‐H)2Ni] (C4), respectively. All compounds have been characterized by micro and spectroscopic analysis. The molecular structure of complexes C1–C3 has also been determined by single crystal X‐ray diffraction data. The utility of complexes C1–C4 were evaluated for the N‐alkylation of aniline with benzyl alcohols, and for 1,2‐disubstituted benzimidazoles synthesis. The obtained results indicate that complex C1 showed better catalytic activity in both N‐alkylation of amines with benzyl alcohols [catalyst loading: 2.0 mol %; Yield up to 92 %], and for 1,2‐disubstituted benzimidazoles derivatives [catalyst loading: 2.0 mol %; Yield up to 94 %)]. The mechanistic studies suggested that the reaction works through hydrogen borrowing from benzyl alcohol and its subsequent utilization for in situ reduction of imine. The experimentally observed catalytic reactivity patterns of complexes C1–C4 have found in good agreement with the HOMO‐LUMO energy gaps obtained by DFT analysis of corresponding complexes. [ABSTRACT FROM AUTHOR]

An air‐stable, inexpensive, and isolable cobalt(II) complex (C1) of N‐((1‐methyl‐1H‐imidazol‐2‐yl)methyl)‐2‐(phenylselanyl)ethan amine (L1) was synthesized and characterized. The complex was used to catalyze a one‐pot cascade reaction between 2‐(2‐aminophenyl)ethanols and benzyl alcohol derivatives. Interestingly, 2‐aryl‐3‐formylindole derivatives were formed instead of N‐alkylated or C‐3 alkylated indoles. A broad substrate scope can be activated using this protocol with only 5.0 mol % catalyst loading to achieve up to 87 % yield of 2‐aryl‐3‐formylindole derivatives. The mechanistic studies suggested that the reaction proceeds through tandem imine formation followed by cyclization. [ABSTRACT FROM AUTHOR]

An air‐stable, inexpensive, and isolable cobalt(II) complex (C1) of N‐((1‐methyl‐1H‐imidazol‐2‐yl)methyl)‐2‐(phenylselanyl)ethan amine (L1) was synthesized and characterized. The complex was used to catalyze a one‐pot cascade reaction between 2‐(2‐aminophenyl)ethanols and benzyl alcohol derivatives. Interestingly, 2‐aryl‐3‐formylindole derivatives were formed instead of N‐alkylated or C‐3 alkylated indoles. A broad substrate scope can be activated using this protocol with only 5.0 mol % catalyst loading to achieve up to 87 % yield of 2‐aryl‐3‐formylindole derivatives. The mechanistic studies suggested that the reaction proceeds through tandem imine formation followed by cyclization. [ABSTRACT FROM AUTHOR]

In this report, we have synthesized two new NCS pincer ligands by the Schiff base reaction of 3‐((phenylthio)methoxy)benzaldehyde (P) with alkyl amines (tbutylamine (L1) and 1‐adamantylamine (L2)). The palladium pincer complexes (tbutylamine=C1 and 1‐adamantylamine=C2) of these ligands were synthesized by their reaction with PdCl2(CH3CN)2 precursor. The newly synthesized ligands and complexes were characterized using various analytical and spectroscopic techniques such as 1H, 13C{1H} Nuclear Magnetic Resonance (NMR), Ultraviolet–visible (UV‐Visible), Fourier Transform Infrared (FTIR) Spectroscopy, and High‐Resolution Mass Spectrometry (HRMS). The structure of the ligand and its coordination mode with palladium precursor were studied with the help of single‐crystal X‐ray diffraction. The complexes showed distorted square planar geometry around the palladium center. The palladium pincer complexes were used as catalysts for the regioselective cross‐dehydrogenative alkenation of 2‐arylthiophene derivatives. The complex C2, where sterically bulky adamantyl ligand is part of the side arm showed a higher yield of alkenation reaction. Only 2.5 mol% catalyst loading was sufficient to achieve 74–95 % yields of desired products with excellent functional group tolerance under mild reaction conditions. The poisoning experiments (PPh3 and Hg) showed the homogeneous nature of the catalytic process. The plausible mechanism of the reaction was proposed based on the control experiments and time‐dependent HRMS studies. [ABSTRACT FROM AUTHOR]

Herein, we present a hassle-free approach to synthesize Ni nanoparticles (NPs) and support them onto oxidized charcoal (OC) to produce Ni-oxidized charcoal nanomaterials (Ni-OC). Subsequently, Ni-NPs and Ni-OCs are characterized using powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron (XPS) spectroscopy, transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) techniques. The size distribution curve reveals that the diameter of the Ni-NPs embedded in OC falls in the range of 3–7 nm. Surface area studies show that Ni-NPs and Ni-OC have specific surface areas of 36.5 and 248.9 m2/g, respectively. Interestingly, Ni-OC exhibits the soft ferromagnetic nature of nickel. Ni-NPs and Ni-OC are used as catalysts for the N-alkylation reaction between aniline and benzyl alcohol. The Ni-OC nanomaterials show excellent yields (70–92%) of N-alkylated products. Notably, a catalyst loading of only 0.0482 mmol is sufficient to activate a broad substrate scope with a large functional group tolerance. In addition, the developed synthetic protocol can be further exploited for the catalytic synthesis of 1,2-disubstituted benzimidazole derivatives in excellent yields (65–89%) and effective functional group tolerance. It has been observed that the hydrogen-borrowing mechanism powers both catalytic processes. The Ni-OC exhibits outstanding catalytic reusability and magnetic recoverability for the N-alkylation reaction of aniline with benzyl alcohol for more than seven reaction cycles. In contrast to Ni-NPs, the Ni-OC catalyst exhibits higher catalytic activity for the N-alkylation reaction. This could be explained by the interactions between Ni-NPs and the functional groups available on the oxidized charcoal, which enhance the surface area of the Ni-OC. [ABSTRACT FROM AUTHOR]

Herein, we have reported the synthesis of a macrocyclic organosulfur ligand (L1) having a seventeen‐membered macrocyclic ring. Subsequently, the corresponding trans‐palladium complex (C1) of bulky macrocyclic organosulfur ligand (L1) was synthesized by reacting it with PdCl2(CH3CN)2 salt. The newly synthesized ligand and complex were characterized using various analytical and spectroscopic techniques. The complex showed a square planar geometry with trans orientation of two ligands around the palladium center. The complex possesses intramolecular SCH...Cl interactions of 2.648 Å between the macrocyclic ligand and palladium dichloride. The potential energy surface (PES) for the rotational process of C1 suggested a barrier of ~23.81 kcal/mol for chlorine rotation. Furthermore, the bulky macrocyclic organosulfur ligand stabilized palladium complex (C1) was used as a catalyst (2.5 mol %) for α‐olefination of nitriles by primary alcohols. The α,β‐unsaturated nitrile compounds were found to be the major product of the reaction (57–78 % yield) with broad substrate scope and large functional group tolerance. Notably, the saturated nitrile product was not observed during the reaction. The mechanistic studies suggested the formation of H2 and H2O as only by‐products of the reaction, thereby making the protocol greener and sustainable. [ABSTRACT FROM AUTHOR]

This report describes the synthesis of a seventeen-membered macrocyclic ring containing ligand (L1) by the reaction of 1,8-bis(2-(chloromethyl)phenoxy)octane with selenium powder. The trans-palladium dichloride complex (C1) of the macrocyclic selenium ligand was synthesized from its reaction with the Pd(CH3CN)2Cl2 precursor. The formation of the ligand and complex was authenticated with the help of various analytical techniques like 1H and 13C{1H} NMR, HRMS, FTIR, UV-visible spectroscopy, and elemental analysis. The structure of the ligand and its coordination mode with the palladium precursor were authenticated with the help of single crystal X-ray diffraction. The complex possesses a distorted square planar geometry around the palladium center. The new ligand and complex are air and moisture insensitive and stable at room temperature for over three months. The variable temperature NMR data and computational studies suggest selenium inversion in the palladium complex (C1) with an inversion barrier of ∼22.6 kcal mol−1. The palladium complex C1 was used as a catalyst for the dehydroxymethylation of long alkyl chain containing dihydroxy compounds. Generally, two separate catalysts are used for dehydroxymethylation (one for the oxidation of the alcohol and the other for the decarbonylation of the aldehyde). Here a single catalyst shows the dual action of dehydroxymethylation with up to 91% yield under only 5.0 mol% catalyst loading. A broad substrate scope can be achieved with good functional group tolerance. The PPh3 and Hg poisoning tests suggest the homogeneous nature of the reaction. Interestingly, the same long alkyl chain containing dihydroxy compounds were reported to undergo macrolactonization when reacted with a ruthenium catalyst. [ABSTRACT FROM AUTHOR]

An air-stable, inexpensive, and isolable cobalt(II) complex (C1) of N-((1-methyl-1H-imidazol-2-yl)methyl)-2-(phenylselanyl)ethan amine (L1) was synthesized and characterized. The complex was used to catalyze a one-pot cascade reaction between 2-(2-aminophenyl)ethanols and benzyl alcohol derivatives. Interestingly, 2-aryl-3-formylindole derivatives were formed instead of N-alkylated or C-3 alkylated indoles. A broad substrate scope can be activated using this protocol with only 5.0 mol % catalyst loading to achieve up to 87 % yield of 2-aryl-3-formylindole derivatives. The mechanistic studies suggested that the reaction proceeds through tandem imine formation followed by cyclization., (© 2024 Wiley-VCH GmbH.)

Herein, we have reported the synthesis of a macrocyclic organosulfur ligand (L1) having a seventeen-membered macrocyclic ring. Subsequently, the corresponding trans-palladium complex (C1) of bulky macrocyclic organosulfur ligand (L1) was synthesized by reacting it with PdCl 2 (CH 3 CN) 2 salt. The newly synthesized ligand and complex were characterized using various analytical and spectroscopic techniques. The complex showed a square planar geometry with trans orientation of two ligands around the palladium center. The complex possesses intramolecular SCH…Cl interactions of 2.648 Å between the macrocyclic ligand and palladium dichloride. The potential energy surface (PES) for the rotational process of C1 suggested a barrier of ~23.81 kcal/mol for chlorine rotation. Furthermore, the bulky macrocyclic organosulfur ligand stabilized palladium complex (C1) was used as a catalyst (2.5 mol %) for α-olefination of nitriles by primary alcohols. The α,β-unsaturated nitrile compounds were found to be the major product of the reaction (57-78 % yield) with broad substrate scope and large functional group tolerance. Notably, the saturated nitrile product was not observed during the reaction. The mechanistic studies suggested the formation of H 2 and H 2 O as only by-products of the reaction, thereby making the protocol greener and sustainable., (© 2023 Wiley-VCH GmbH.)

This report describes the synthesis of a seventeen-membered macrocyclic ring containing ligand (L1) by the reaction of 1,8-bis(2-(chloromethyl)phenoxy)octane with selenium powder. The trans -palladium dichloride complex (C1) of the macrocyclic selenium ligand was synthesized from its reaction with the Pd(CH 3 CN) 2 Cl 2 precursor. The formation of the ligand and complex was authenticated with the help of various analytical techniques like 1 H and 13 C{ 1 H} NMR, HRMS, FTIR, UV-visible spectroscopy, and elemental analysis. The structure of the ligand and its coordination mode with the palladium precursor were authenticated with the help of single crystal X-ray diffraction. The complex possesses a distorted square planar geometry around the palladium center. The new ligand and complex are air and moisture insensitive and stable at room temperature for over three months. The variable temperature NMR data and computational studies suggest selenium inversion in the palladium complex (C1) with an inversion barrier of ∼22.6 kcal mol -1 . The palladium complex C1 was used as a catalyst for the dehydroxymethylation of long alkyl chain containing dihydroxy compounds. Generally, two separate catalysts are used for dehydroxymethylation (one for the oxidation of the alcohol and the other for the decarbonylation of the aldehyde). Here a single catalyst shows the dual action of dehydroxymethylation with up to 91% yield under only 5.0 mol% catalyst loading. A broad substrate scope can be achieved with good functional group tolerance. The PPh 3 and Hg poisoning tests suggest the homogeneous nature of the reaction. Interestingly, the same long alkyl chain containing dihydroxy compounds were reported to undergo macrolactonization when reacted with a ruthenium catalyst.