Pd Nanoparticles Capped with [CpPd(II)Cl]₂ Complexes for Hydrogenation and Acid-Free Acetalization of α,β-Unsaturated Aldehydes

Abstract

Hierarchical bottom-up self-assembly of nanoparticles by wet chemistry methods is a promising approach to the preparation of engineered metal–ligand networks with advanced catalytic properties. Here, we developed a facile strategy to synthesize self-organized metal–ligand Pd(0)–[CpPd­(II)­Cl]2 nanoreactor through a redox and in situ transmetalation reaction between palladium ions and titanium ions. The obtained integrated metallic Pd(0) nanoparticles with organic [CpPd­(II)­Cl]2 capping ligands have been systematically characterized. The self-assemblies can not only serve as a support providing physical barriers against aggregation of ultrasmall Pd nanoparticles with good stability while keeping Pd nanoparticle core highly accessible but can also act as an efficient bifunctional nanoreactor for the first realization of selective hydrogenation and acid-free acetalization cascade reaction. Because of the combination of the two functions of metallic Pd(0) nanoparticles and Lewis acid Pd­(II) ions in the [CpPd­(II)­Cl]2 ligands, the obtained integrated Pd(0)–[CpPd­(II)­Cl]2 nanoreactor exhibits excellent hydrogenation selectivity and activity (up to 66%–98% yield) in the synthesis of the acetal derivatives from broad substrates of α,β-unsaturated aldehydes and alcohols under mild conditions. Our work has successfully engineered a metal–ligand ensemble to obtain an attractive bifunctional heterogeneous catalyst for cascade organic transformations, presenting a significant step toward the attainment of green and sustainable chemical reactions.

The Complex Compound of Amino Acids With Titanium (III) as a Method to Control and Synthesis of Different Structures of TiO2 Nanoparticles; Usage as Photocatalysts to Oxidize Alcohols to Aldehyde

“…Many methods have been created by scientists for the synthesis of titanium dioxide nanoparticles, including sol-gel, microwave, micelle, aerogel, hydrothermal, chemical vapour deposition, physical vapour deposition, electrochemical accumulation, sonochemical, and microwave. Organometallic complex compounds are also proper initial products for the synthesis of nanoparticles, with the advantages of low temperature, less time, purity, and environmentally friendly [9][10][11][12][13][14][15][16].…”