Maravanji Shivaramaiah Balakrishna

Solar-driven CO ₂ reduction offers a sustainable route to carbon neutrality by converting greenhouse gases into value-added fuels.

This paper highlights the catalytic utility of Pd ^II and Pt ^II complexes of a triazolyl–pyridyl phosphine ligand, wherein in situ generated Pd nanoparticles enable efficient and stereoselective transfer semi-hydrogenation of alkynes using ethanol.

A tridentate amide-pyridine-monophosphine ligand, {(o-PPh₂)C₆H₄C(O)N(H)CH₂(C₅H₄N)} (1), has been employed to synthesize a series of Ru^II and Ru^III pincer complexes. Reaction of ligand 1 with [RuCl₂(DMSO)₄] and [RuCl₂(PPh₃)₃] yielded [RuCl(C₁₂H₈N₂){(PNN)-κ³-P,N,N}] (2) and [RuCl₂(PPh₃){(PNN)-κ³-P,N,N}] (3), respectively, while treatment with [RuHCl(CO)(PPh₃)₃] under varied conditions afforded pincer-type complexes [RuCl(CO)(PPh₃){(PNN)-κ³-P,N,N}] (4), [RuH(CO)(PPh₃){(PNN)-κ³-P,N,N}] (5), and [Ru(Cl)₂(CO){(PNN)-κ³-P,N,N}]Cl (6). Ligand 1 upon reaction with [Ru(p-cymene)Cl₂]₂ and [RuCl₂(PPh₃)₃] under aerobic reaction conditions afforded [RuCl(CH₃CN)₂{(o-PPh₂)C₆H₄C(O)NC(O)(C₅H₄N)}-κ³-P,N,N] (7) and [RuCl₂(CH₃OH){(o-PPh₂)C₆H₄C(O)NC(O)(C₅H₄N)}-κ³-P,N,N] (8) complexes, respectively, showing base- and additive-free benzylic C-H oxidation at room temperature. Complexes 4 and 5 were employed in the hydration of nitriles to amides. Mechanistic studies support a [Ru-H] active species facilitating water activation through a [Ru-H···H-OH] dihydrogen bond, enabling nucleophilic attack on the coordinated nitrile. The catalyst system operates at low loadings, tolerating both electron-rich and electron-deficient nitriles.

Copper( i ) complexes stabilised by PNO-type ligands showed excellent catalytic activity for the N -arylation of indoles and carbazoles, and in the N -alkylation of indoles, via in situ generated copper nanoparticles.

This study reports the synthesis of Ru^II complexes containing amide-based phosphine ligands and their catalytic activity in benzimidazole synthesis, with product selectivity influenced by alcohol concentration.

In this study, we report the synthesis and structural characterization of a series of transition metal complexes derived from two pincer‐type ligands: {(o‐PPh₂)C₆H₄C(O)NH(C₉H₆N)} (1) and {(o‐Ph₂PC₆H₄C(O)N(H)C₆H₄PPh₂‐o)} (2). Treatment of Ligand 1 with [Rh (acac)(CO)₂] afforded rhodium pincer complex [Rh (CO){(o‐PPh₂)C₆H₄C(O)N(C₉H₆N)}κ³‐P,N,N] (3). Ligand 1, upon reaction with [Ru(H)(CO)(Cl)(PPh₃)₃] in THF, yielded the ruthenium complex [Ru (PPh₃)(CO)(Cl){(o‐PPh₂)C₆H₄C(O)N(C₉H₆N)}κ³‐P,N,N] (4), while its reaction with [Ru (Cl)₂(PPh₃)₃] in methanol afforded a Ru^III complex, [Ru (CH₃OH)(Cl)₂{(o‐PPh₂)C₆H₄C(O) N(C₉H₆N)}κ³‐P,N,N] (5). Ligand 2, when reacted with CuI in a 1:1 M ratio in a CH₂Cl₂/CH₃CN (1:1 v/v) mixture, yielded the dimeric complex [CuI(o‐PPh₂)C₆H₄C(O) N(H)CH₂C₆H₄(o‐PPh₂)]₂ (6). Increasing the CuI to ligand ratio to 2:1 yielded the tetrameric complex [Cu₄(μ₂‐I)₂(μ₃‐I)₂{(o‐PPh₂)C₆H₄C(O)NCH₂C₆H₄ (o‐PPh₂)}₂‐P,P] (7). The reaction of Ligand 2 with two equivalents of [AuCl (SMe₂)] produced a binuclear gold complex, [AuCl{(o‐PPh₂)C₆H₄C(O)N(H)CH₂C₆H₄{(o‐PPh₂)}AuCl] (8). Furthermore, Ligand 2 underwent complexation with [Rh (acac)(CO)₂] and [Mn₂(CO)₁₀] to afford PNP‐type pincer complexes [RhCO{(o‐PPh₂)C₆H₄C(O)NCH₂C₆H₄(o‐PPh₂)}κ³‐P,N,P] (9) and [Mn (CO)₃{(o‐PPh₂)C₆H₄ C(O)NCH₂C₆H₄(o‐PPh₂)}κ³‐P,N,P] (10) respectively. Notably, the rhodium PNN pincer Complex 3 was successfully employed as a catalyst in the additive‐free hydrophosphination of phenylacetylenes, providing a more straightforward and operationally simple methodology for this transformation.

This work reports a Ru(ii)-catalyzed, microwave-assisted method for C3-alkylation of indoles and epoxide ring opening, followed by α-alkylation with alcohols under mild conditions.

This manuscript describes the C-alkylation of 9H-fluorene and the synthesis of bis(indolyl)methane derivatives catalysed by the nickel complex [(NiCl){(P^tBu₂)N(H)N-κ³-P,N,N}]OTf (hereafter referred to as Ni2). This efficient protocol offers several advantages, including low catalyst loading, and mild reaction conditions. It also offers a broad substrate scope (encompassing aliphatic, aromatic, and secondary alcohols), high functional group compatibility, and excellent chemoselectivity. The approach also enables post-functionalization of C-alkylated fluorenes and has been successfully applied to the synthesis of medicinally relevant indole derivatives to explore its potential applications. Mechanistic insights were obtained through control experiments. The results suggest that the reaction proceeds via metal–ligand cooperation within the catalytic cycle, and the formation of a nickel hydride intermediate was further confirmed by NMR and HRMS analysis.