Selenoether ligand assisted Heck catalysis

Hydrogen-bonded linear chain assemblies of palladium(II)-selenoether complexes: solid state aggregates as templates for nano-structural Pd17Se15 leading to efficient electrocatalytic activity

A analogous series of 2-(3,5-dimethylpyrazol-1-yl)phenyl substituted selenoether complexes of palladium [PdCl2(RSeC6H4dmpz)]; (R = CH2COOH (1), CH2CH2COOH (2), and CH2CH2OH (3); dmpz = dimethylpyrazole) were ably synthesized in a facile manner and exhaustively characterized. Insight into molecular structures of these complexes was keenly probed through single crystal X-ray diffraction (XRD) analysis, unfolding the structural scaffolds and laying into molecular aggregation, availed through hydrogen bonding interactions borne out of tethered protic groups. The complexes were converted to capping free palladium selenide (Pd17Se15) nanoparticles through pyrolysis and evaluated for their electrocatalytic efficacy towards the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER) and methanol oxidation reaction (MOR) in alkaline medium. In an alkaline medium, PSNP1 (Pd17Se15) obtained from the hydrogen bonded aggregate of complex PdCl2L1 (1) produced good HER activity. PSNP1 had a little decrease in current density after 300 continuous cycles, which proves that the catalyst presents high stability in the recycling process. For the electrocatalytic oxidation of CH3OH, the electrocatalytic rate constant (k) obtained was 0.3 × 103 cm3 mol-1 s-1.

Phosphine and Selenoether peri-Substituted Acenaphthenes and Their Transition-Metal Complexes: Structural and NMR Investigations

A series of peri-substituted acenaphthene-based phosphine selenoether bidentate ligands Acenap(iPr2P)(SeAr) (L1-L4, Acenap = acenaphthene-5,6-diyl, Ar = Ph, mesityl, 2,4,6-trisopropylphenyl and supermesityl) were prepared. The rigid acenaphthene framework induces a forced overlap of the phosphine and selenoether lone pairs, resulting in a large magnitude of through-space 4JPSe coupling, ranging from 452 to 545 Hz. These rigid ligands L1-L4 were used to prepare a series of selected late d-block metals, mercury, and borane complexes, which were characterized, including by multinuclear NMR and single-crystal X-ray diffraction. The Lewis acidic motifs (BH3, Mo(CO)4, Ag+, PdCl2, PtCl2, and HgCl2) bridge the two donor atoms (P and Se) in all but one case in the solid-state structures. Where the bridging motif contained NMR-active nuclei (11B, 107Ag, 109Ag, 195Pt, and 199Hg), JPM and JSeM couplings are observed directly, in addition to the altered JPSe in the respective NMR spectra. The solution NMR data are correlated with single-crystal diffraction data, and in the case of mercury(II) complexes, they are also correlated with the solid-state NMR data and coupling deformation density calculations. The latter indicate that the through-space interaction dominates in free L1, while in the L1HgCl2 complex, the main coupling pathway is via the metal atom and not through the carbon framework of the acenaphthene ring system.

An experimental and computational comparison of phosphorus- and selenium-based ligands for catalysis

To compare and contrast the bonding and reactivity of organoselenium ligands with organophosphines in coordination complexes, a new palladium(II) complex of the Se,N-chelating ligand o-(NH2)(X)C6H4 (X = SePh, 2) was prepared. Its characterization by NMR spectroscopy, single-crystal X-ray diffraction, and density functional theory calculations is contrasted with the PdII complex of the related P,N- chelating ligand (X = PPh2, 1). These techniques indicate that the phenylseleno moiety is a weaker σ donor to the PdCl2 fragment than the diphenylphosphino group. Both complexes were suitable to catalyze the Suzuki–Miyaura coupling of p-tolylboronic acid and 4-bromobenzaldehyde.

Infrared irradiation assisted both the synthesis of ( Z)-(aminomethyl)(aryl)phenylhydrazones via the Mannich coupling reaction and their application to the palladium-catalyzed Heck reaction

The synthesis of arylhydrazones 1a–h assisted with infrared irradiation (IR) under solvent-free conditions is herein reported, and their catalytic action in the palladium-catalyzed and IR-assisted Heck coupling reaction are also evaluated.

Bis(chalcogenones) as pincer ligands: isolation and Heck activity of the selone-ligated unsymmetrical C,C,Se–Pd pincer complex

The reaction of meta-phenylene-bis(1-methyl-1H-imidazole-2(3H)-selone) with [Pd₂(μ-Cl)₂(2-C₆H₄CH₂NMe₂)₂] in dry benzene and glacial acetic acid resulted in the formation of an unsymmetrical 5,6-membered C,C,Se–Pd(ii) pincer complex.

Facile synthesis of pyrazole- and benzotriazole-containing selenoethers

Azole-containing selenoethers, 1,5-bis(3,5-dimethylpyrazol-1-yl)-3-selena pentane and 1,3-bis(1,2,3-benzotriazol-1-yl)-2-selena propane were prepared by the reaction of corresponding tosylate or chloride with sodium selenide generated in situ from elemental selenium and sodium formaldehydesulfoxylate (rongalite).

The aminocyclodextrin/Pd(OAc)2 complex as an efficient catalyst for the Mizoroki-Heck cross-coupling reaction

An aminocyclodextrin/Pd(OAc)2 complex is used as an efficient, reusable catalyst in the Mizoroki-Heck reaction of aryl halides/triflates with olefins to give carbon-carbon-coupled products in good to excellent yields. This simple, efficient catalytic system is applicable to a wide range of aryl and heteroaryl halides/triflates and olefins. This environmentally benign procedure is less hazardous, milder, uses a catalytic amount of ligand and Pd(OAc)2 , avoids an inert atmosphere, and catalyst recovery and reusability are achieved.