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 a-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

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)]·nH2O} 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

Kinetic investigations of the mechanism of dihydrogen driven catalytic reduction of methylene blue, safranine O, methyl viologen and ferricyanide using platinum carbonyl cluster anions (Chini-clusters) as catalyst

[Bu4N]2[Pt12(CO)24] (1) catalyses the selective reduction of electron acceptors (S), methylene blue (MB+), safranine O (Saf+), methyl viologen (MV2+) and ferricyanide by dihydrogen. Macroscopic rate investigations for the cationic substrates in DMF, and for ferricyanide in DMSO have been carried out. In all cases, kobs is given by k1 [S] + k2, indicating that there are two catalytic cycles. In one of them, the formation of a complex between S and [Pt12(CO)24]2- in the rate determining step (rate constant k1) is followed by electron transfer and/or other fast steps. In the other catalytic cycle, the rate determining step (rate constant k2) involves formation of the solvated cluster anion [Pt12(CO)24]2-. The solvated cluster then undergoes fast reduction by dihydrogen and other reactions. The relative contributions of these two cycles depend on the substrate, and for MB+, Saf+, MV2+ and [Fe(CN)6]3- the contribution of the second cycle is about 99%, 55%, 77% and 97%, respectively. Both k1 and k2 of ferricyanide are about three orders of magnitude smaller than those of the cationic electron acceptors. The rates of reduction of MB+ and Saf+ have also been studied in the presence of added water. Rates increase as the presence of water provides an additional pathway for the reduction of [Pt12(CO)24]2- to [Pt9(CO)18]2-

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 a-ketoesters with cluster derived heterogeneous catalysts

Effect of various particlization scenarios on anisotropic flow and particle production using UrQMD hybrid model

We discuss the effect of various particlization scenarios available in the hybrid ultrarelativistic quantum molecular dynamics (UrQMD) event generator on different observables in non-central ($b$ $=$ 5--9 $fm$) Au + Au collisions in the beam energy range 1A-158A GeV. Particlization models switch fluid dynamic description to the transport description using various hypersurface criteria. In addition to particlization models, various equations-of-state (EoS) provided by the UrQMD hybrid model were employed. The observables examined in this paper include the excitation function of anisotropic coefficients such as directed ($v_{1}$) and elliptic flow ($v_{2}$), particle ratios of the species, and the shape of net-proton rapidity spectra at mid-rapidity. The results obtained here can help predict and compare the measurements provided by future experiments at the Facility for Antiproton and Ion Research (FAIR) and the Nuclotron-based Ion Collider fAcility (NICA) once the data becomes available. We also study the most suitable combination of the particlization model and EoS, which best describes the experimental measurements.Comment: 11 pages, 8 figure

Molecular orbital calculations on [HRu<SUB>3</SUB>(CO)<SUB>9</SUB>(PhNCO)]<SUP>-</SUP> 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

Polyethersulfone supported titanium complexes as ethylene polymerization catalysts

Polyethersulfone has been used as the support to anchor TiCl4 or Cp2TiCl2 through dative 'O-Ti' bond. The supported complexes in combination with methylaluminoxane are effective ethylene polymerization catalysts. The polyethylene made by the supported catalysts, especially the titanocene-derived catalyst, has low polydispersity indicating single site character

Dynamics of Hot QCD Matter -- Current Status and Developments

The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe, just after the Big Bang. In the meantime, advancements in theoretical works and computing capability extend our wisdom about the hot-dense QCD matter and its dynamics through mathematical equations. The exchange of ideas between experimentalists and theoreticians is crucial for the progress of our knowledge. The motivation of this first conference named "HOT QCD Matter 2022" is to bring the community together to have a discourse on this topic. In this article, there are 36 sections discussing various topics in the field of relativistic heavy-ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This article begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an overview of experiment results.Comment: Compilation of the contributions (148 pages) as presented in the `Hot QCD Matter 2022 conference', held from May 12 to 14, 2022, jointly organized by IIT Goa & Goa University, Goa, Indi