Heterobimetallic Nanoparticles Research Articles

C–O Bond Activation by Nickel–Palladium Hetero-Bimetallic Nanoparticles for Suzuki–Miyaura Reaction of Bioactive Heterocycle-Tethered Sterically Hindered Aryl Carbonates

Ni–Pd binary nanoclusters are reported for the activation of the C–O bond for Suzuki–Miyaura cross-coupling of bioactive heterocycle-tethered sterically hindered aryl carbonates with aryl boronic acids. The reaction does not take place in the presence of either the Pd or Ni salts/complexes or the individual Pd or Ni nanoparticles, indicating ensembling cooperativity between the Pd and Ni nanoparticles in activating the C–O bond.

Active and Recyclable Catalytic Synthesis of Indoles by Reductive Cyclization of 2-(2-Nitroaryl)acetonitriles in the Presence of Co-Rh Heterobimetallic Nanoparticles with Atmospheric Hydrogen under Mild Conditions.

A cobalt-rhodium heterobimetallic nanoparticle-catalyzed reductive cyclization of 2-(2-nitroaryl)acetonitriles to indoles has been achieved. The tandem reaction proceeds without any additives under the mild conditions (1 atm H2 and 25 °C). This procedure could be scaled up to the gram scale. The catalytic system is significantly stable under these reaction conditions and could be reused more than ten times without loss of catalytic activity.

Cobalt/Rhodium Heterobimetallic Nanoparticle‐Catalyzed Oxidative Carbonylation of Amines in the Presence of Carbon Monoxide and Molecular Oxygen to Ureas

Abstractmagnified imageAn environmentally friendly oxidative carbonylation of aliphatic and aromatic primary amines to ureas has been successfully achieved in the presence of a catalytic amount of cobalt/rhodium heterobimetallic nanoparticles without any promoters. The catalyst system could be reused with only a slight loss of catalytic activity.

Allenic Pauson—Khand Reaction Catalyzed by Cobalt—Rhodium Heterobimetallic Nanoparticles.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Allenic Pauson-Khand Reaction Catalyzed by Cobalt-Rhodium Hetero­bimetallic Nanoparticles

Pauson-Khand reaction of allenynes, catalyzed by Co-Rh heterobimetallic nanoparticles, was developed for the synthesis of [5.6]- and [5.7]-bicyclic enones. The cyclization occurred selectively with the distal double bond of the allene. The catalytic system could be used at least six times without loss of catalytic activity.

The Pauson—Khand‐Type Reaction Catalyzed by Transition Metal Nanoparticles

AbstractFor Abstract see ChemInform Abstract in Full Text.

Cyclohydrocarbonylation of Substituted Alkynes and Tandem Cyclohydrocarbonylation—CO Insertion of α‐Keto Alkynes Catalyzed by Immobilized Co—Rh Heterobimetallic Nanoparticles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Immobilized Co/Rh Heterobimetallic Nanoparticle‐Catalyzed Pauson–Khand‐Type Reaction

AbstractCo/Rh heterobimetallic nanoparticles were prepared from cobalt‐rhodium carbonyl clusters [Co2Rh2(CO)12 and Co3Rh(CO)12] and immobilized on charcoal. HR‐TEM revealed that the size of the heterobimetallic nanoparticles was ca. 2 nm and ICP‐AES analysis showed a 2 : 2 and a 3 : 1 cobalt‐rhodium stoichiometry (Co2Rh2 and Co3Rh1) in the heterobimetallic nanoparticles. The Co/Rh heterobimetallic nanoparticles immobilized on charcoal were used as a catalyst in the Pauson–Khand‐type reaction under 1 atm of CO. The catalytic reactivity was highly dependent upon the ratio of Co : Rh with the highest reactivity being observed when the ratio was 2 : 2 (Co2Rh2). The Co2Rh2 immobilized catalyst is quite an effective catalyst for intra‐ and intermolecular Pauson–Khand‐type reactions. When the immobilized Co2Rh2 catalyst was used as a catalyst in the Pauson–Khand‐type reaction in the presence of an aldehyde instead of carbon monoxide, the catalytic system was highly efficient. When the reaction was carried out in the presence of chiral diphosphines, ee values up to 87% were observed. The catalytic system can be reused at least five times in the presence of chiral diphosphines without loss of catalytic activity and enantioselectivity. The addition of Hg(0), a known heterogeneous catalyst poison, completely inhibits further catalysis. Thus, an environmentally friendly and sustainable process was developed.

Synthesis of Coumarins Catalyzed by Heterobimetallic Co/Rh Nanoparticles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

The Pauson-Khand-Type Reaction Catalyzed by Transition Metal Nanoparticles

In this account, we survey our work on the use of transition metal nanoparticles as catalysts in Pauson-Khand-type reactions. Cobalt nanoparticles and Co/Ru, Co/Rh, and Co/Pd het- erobimetallic nanoparticles have been used in Pauson-Khand-type reactions and related tandem reactions. In the case of Co/Ru nano- particles, pyridylmethylformate can be used instead of carbon mon- oxide. We have developed environmentally friendly processes. The use of Co/Rh heterobimetallic nanoparticles allows the develop- ment of a new type of (2+2+1) cycloaddition of an a,b-unsaturated aldehyde with an alkyne.

Cyclohydrocarbonylation of substituted alkynes and tandem cyclohydrocarbonylation–CO insertion of α-keto alkynes catalyzed by immobilized Co–Rh heterobimetallic nanoparticles

The use of cobalt-rhodium (Co(2)Rh(2)) heterobimetallic nanoparticles in the cyclohydrocarbonylation of substituted alkynes and tandem cyclohydrocarbonylation-CO insertion of alpha-keto alkynes to give 2(3H)- or 2(5H)-furanones is described.

Synthesis of Coumarins Catalyzed by Heterobimetallic Co/Rh Nanoparticles

Described here is the use of cobalt/rhodium (Co2Rh2) heterobimetallic nanoparticles in the catalytic synthesis of coumarins via cyclocarbonylation of alkynes with 2-iodophenol under 1 atm of carbon monoxide and reaction of phenol with propiolic ­esters.

A Pauson—Khand‐Type Reaction Between Alkynes and Olefinic Aldehydes Catalyzed by Rhodium/Cobalt Heterobimetallic Nanoparticles: An Olefinic Aldehydes as an Olefin and CO Source.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Pauson-Khand-type reaction between alkynes and olefinic aldehydes catalyzed by rhodium/cobalt heterobimetallic nanoparticles: an olefinic aldehyde as an olefin and CO source.

Co/Rh (Co:Rh = 2:2) heterobimetallic nanoparticles derived from Co(2)Rh(2)(CO)(12) react with alkynes and alpha,beta-unsaturated aldehydes such as acrolein, crotonaldehyde, and cinnamic aldehyde and release products resulting from [2 + 2 + 1]cycloaddition of alkyne, carbon monoxide, and alkene. alpha,beta-Unsaturated aldehydes act as a CO and alkene source. These reactions produce 2-substituted cyclopentenones.

Nanoparticles of Prussian blue ferritin: a new route for obtaining nanomaterials.

The dissociation of apoferritin into subunits at pH 2 followed by its re-formation at pH 8.5 in the presence of hexacyanoferrate(III) gave rise to a solution containing hexacyanoferrate(III) trapped within the apoferritin and hexacyanoferrate(III) outside it. The addition of Fe(II) to the dialyzed solution resulted in the appearance of the characteristic Prussian blue color. The UV-vis spectrum of this solution showed a broad band centered at 710 nm, and the IR spectrum contained a broad-medium band at 2083 cm(-1). Both features are consistent with the charge-transfer band and the C[bond]N stretching mode in the Fe(II)[bond]CN[bond]Fe(III) fragment of PB. TEM images of the obtained Prussian blue solution showed discrete spherical electron dense iron particles with an average size of about 5 nm. This represents a new route for preparing metallic nanoparticles that offers control over the size and protection against aggregation. Moreover, the fact that the particles are obtained by reaction of hexacyanoferrate(III) and iron(II) building blocks opens up the possibility of obtaining not only homo- but also heterobimetallic nanoparticles.