Articles written in Journal of Chemical Sciences

• Some aspects of the chemistry of platinum carbonyl clusters

Different aspects of the work carried out on the Chini-clusters are reviewed here. These are: (1) the uses of platinum clusters for the synthesis of hetero-metal clusters, (2) platinum clusters as mediators in pH-driven transport of sodium ions and electrons through a liquid membrane, and (3) asymmetric hydrogenation of α-ketoesters with cluster derived heterogeneous catalysts.

• Chiral rhodium carboxylates as asymmetric hydrogenation catalysts

The comparative catalytic activities of a few chiral rhodium carboxylato complexes in combination with chiral and achiral phosphines are described. In the hydrogenation of α-acetamidocinnamic acid and its methyl ester, differences are observed in turnover numbers and enantioselectivities. Diastereomeric interactions between chiral carboxylato and chiral phosphine moieties resulting in different rates are clearly seen. Arrhenius plots of (+) and (-) DIOP [DIOP = 2,3 isopropylidene 2,3 dihydroxy-1,4bis (diphenylphosphino) butane] with rhodium (-) mandalato complex give markedly different activation energies.

• Molecular orbital calculations on [HRu3(CO)9(PhNCO)] and related clusters

Molecular orbital calculations (EHMO) have been performed on five ruthenium carbonyl clusters considered to be involved in the reductive carbonylation of nitrobenzene. The bonding in the isocyanate cluster, [HRu3(CO)9(HNCO)], is shown to arise mainly from the interaction between the LUMO of HNCO and HOMO of the [HRu3(CO)9] fragment. The relative stabilities of this cluster, two of its isomers and the CO-eliminated cluster [HRu3(CO)9(HN)], are also commented upon. The calculated results are in accordance with empirical kinetic data.

• A water soluble heteropolyoxotungstate as a selective, efficient and environment friendly oxidation catalyst

A series of water soluble Keggin type heteropolyoxotungstates have been tested as oxidation catalysts in aqueous-biphasic media with dilute H2O2 (30%) as the oxygen atom donor, without using any phase transfer agent. The Zn substituted polyoxoanion {(NH4)7Zn0.5[𝛼-ZnO4W11O30ZnO5(OH2)]$.n$H2O} has been found to be the most efficient catalyst, which oxidizes a wide range of organic functionalities with good turnovers and high selectivities. The functionalities that undergo oxidations are: organic sulfides, pyridines, anilines, benzyl alcohols and benzyl halides. The oxidations of sulfides to sulfoxides and/or sulfones have been studied in detail, and a simple kinetic model consisting of two consecutive reactions, is shown to give good fit with the experimental data. In the catalytic system described here product isolation is easy, and the aqueous catalyst solution can be re-used several times with little loss in its efficiency.

• # Journal of Chemical Sciences

Volume 134, 2022
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Posted on July 25, 2019

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