New Palladium Complexes with S- or Se-Containing Schiff-Base Ligands as Efficient Catalysts for the Suzuki–Miyaura Cross-Coupling Reaction of Aryl Bromides with Phenylboronic Acid under Aerobic Conditions

Well-Defined and Highly Effective Nickel Catalysts Coordinated on Tridentate SNO Schiff-Base Derivatives for Alternating Copolymerization of Epoxides and Anhydrides

A series of Ni complexes supported by SNO Schiff-base derivatives were synthesized in this study. Complex synthesis and characterization data are reported herein. Treatment of the pro-ligands [L¹-H = 2-(((2-(methylthio)ethyl)imino)methyl)phenol, L²-H = 2,4-di-tert-butyl-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L³-H = 2-(((2-(methylthio)ethyl)imino)methyl)-4,6-bis(2-phenylpropan-2-yl)phenol, L⁴-H = 4-bromo-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L⁵-H = 4-chloro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with Ni(OAc)₂·4H₂O in refluxing ethanol afforded six-coordinate mono-Ni(II) complexes [L₂ⁿNi] (n = 1-5). Noteworthy, a heptanuclear nickel(II) octacarboxylate species complex 6 and dinuclear nickel complex 6a resulted from treatment of L⁶-H [4-fluoro-2-(((2-(methylthio)ethyl)imino)methyl)phenol] with different metal precursors [Ni(OAc)₂·4H₂O for 6; NiBr₂ for 6a] giving a quantitative yield. The reaction of nickel acetate tetrahydrate and L⁷-H to L⁹-H [L⁷-H = 2-methoxy-6-(((2-(methylthio)ethyl)imino)methyl)phenol, L⁸-H = 5-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol, and L⁹-H = 4-methoxy-2-(((2-(methylthio)ethyl)imino)methyl)phenol] produced the four-coordinate complexes [L₂ⁿNi] (n = 7-9). The highest performing catalyst was complex 3, which was highly efficient for the ring-opening copolymerization of phthalic anhydride (PA) and cyclohexene oxide (CHO) in the presence of a cocatalyst (4-dimethylaminopyridine). In addition, the same copolymerization conditions produced narrowly dispersed polyesters, with high selectivity and polymerization control. In addition to PA-CHO copolymerization, efficient diglycolic anhydride-PA and PA-propene oxide copolymerization was achieved under the same conditions. These catalysts are straightforward to produce and extend the scope of potential substrates.

Metal Coordination Enhances Chalcogen Bonds: CSD Survey and Theoretical Calculations

In this study the ability of metal coordinated Chalcogen (Ch) atoms to undergo Chalcogen bonding (ChB) interactions has been evaluated at the PBE0-D3/def2-TZVP level of theory. An initial CSD (Cambridge Structural Database) inspection revealed the presence of square planar Pd/Pt coordination complexes where divalent Ch atoms (Se/Te) were used as ligands. Interestingly, the coordination to the metal center enhanced the σ-hole donor ability of the Ch atom, which participates in ChBs with neighboring units present in the X-ray crystal structure, therefore dictating the solid state architecture. The X-ray analyses were complemented with a computational study (PBE0-D3/def2-TZVP level of theory), which shed light into the strength and directionality of the ChBs studied herein. Owing to the new possibilities that metal coordination offers to enhance or modulate the σ-hole donor ability of Chs, we believe that the findings presented herein are of remarkable importance for supramolecular chemists as well as for those scientists working in the field of solid state chemistry.

Palladium(ii) complexes of 2,2′-tellurobis(N,N-diphenyl acetamide): efficient catalysts for Suzuki–Miyaura coupling at room temperature under air

Three complexes, [Pd(L2)2Br2](C1), [(L2)PdCl(μ-Cl)2PdCl(L2)](C2), and [Pd(L2)PPh3Cl2](C3), where L2 = 2,2′-tellurobis(N,N-diphenylacetamide), catalyze Suzuki–Miyaura coupling (loading: 0.001 mol % of Pd) of eleven ArX at room temperature under air.

Experimental and theoretical insights into the trans influence of organo-sulfur and -selenium ligands in 5,6-membered palladium(ii) cationic pincer complexes based on iminophosphoranes

The trans influence of organochalcogen ancillary ligands was assessed by experimental and DFT studies in 5,6-membered SNS and SNSe Pd(ii) pincers.

(S)-1-(Benzylselanyl)-3-phenylpropan-2-amine

In the title compound, C16H19NSe, the dihedral angle between the benzene rings is 66.49 (12) and a weak intramolecular N—H...Se hydrogen bond generates an S(6) ring. In the crystal, weak N—H...N hydrogen bonds link the molecules into [100] chains.

Ultra-small palladium nano-particles synthesized using bulky S/Se and N donor ligands as a stabilizer: application as catalysts for Suzuki–Miyaura coupling

Monodispersed ultrasmall Pd nanoparticles synthesized utilizing bulky organochalcogen secondary amines as stabilizers and application in Suzuki coupling of aryl chlorides at low catalyst loading.

Sonogashira (Cu and amine free) and Suzuki coupling in air catalyzed via nanoparticles formed in situ from Pd(ii) complexes of chalcogenated Schiff bases of 1-naphthaldehyde and their reduced forms

The activation of the coupling reactions with the Pd(ii)-complexes (0.05–0.01 mol% loading) is significant in 1–2 h under mild conditions.

Palladacycles of sulfated and selenated Schiff bases of ferrocene-carboxaldehyde as catalysts for O-arylation and Suzuki–Miyaura coupling

Palladacycles of Schiff-bases having a ferrocene core catalyze O-arylation of ArBr and Suzuki–Miyaura coupling of ArBr/Cl with a yield up to 93%.

Synthesis and characterization of a host (a new thiol based dendritic polymer)–guest (Pd nanoparticles) nanocomposite material: an efficient and reusable catalyst for C–C coupling reactions

The catalytic activity of a new thiol based dendritic polymer immobilized on nano silica containing palladium nanoparticles was studied in C–C coupling reactions.

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.

Exhibition of the Brønsted acid–base character of a Schiff base in palladium(ii) complex formation: lithium complexation, fluxional properties and catalysis of Suzuki reactions in water

The Brønsted acid–base character of bis(iminopyrrolylmethyl)amine was shown through the X-ray structures of palladium complexes. The bischelated palladium complex is fluxional as studied by the VT ¹H NMR method and effectively catalyzes Suzuki reactions in water.

Complex of 2-(methylthio)aniline with palladium(II) as an efficient catalyst for Suzuki-Miyaura C-C coupling in eco-friendly water

2-(Methylthio)aniline (L1), a bidentate (S,N) ligand synthesized by the reaction of o-aminothiophenol with methyl iodide, on reacting with Na2PdCl4 in acetone and water gives a complex [PdL1Cl2] (1). Single crystal X-ray diffraction studies have revealed that the geometry of palladium in 1 is nearly square-planar and the ligand L1 is bound to the palladium through S and N in a bidentate coordination mode forming a five membered chelate ring. This complex functions as a thermally and air stable catalyst of high efficiency for Suzuki-Miyaura CC coupling reactions in water. It catalyzes CC coupling between various aryl bromides and phenylboronic acid under mild reaction conditions in water. TON value up to 93,000 has been obtained.

Active versus passive substituent participation in the auxiliary-mediated asymmetric synthesis of an octahedral metal complex

Ambiguous chirality transfer: A surprising reversal of chirality transfer from carbon to metal is reported in the asymmetric synthesis of a chiral ruthenium complex, affording the metal-centered configuration Λ or Δ depending only on the chemical composition of the side chain of a chiral salicyloxazoline auxiliary.