Satyajeet Chaudhury

Kinetics and mechanism of carbothermic reduction of MoO3 to Mo2C

Abstract The kinetics of carbothermic reduction of molybdenum oxide with homogeneously mixed carbon black was studied under non-isothermal heating conditions using a thermobalance. The evolved gases (CO and CO 2 ) were analysed by a gas chromatograph. A mechanism is proposed to explain the stepwise conversion of oxide to carbide. A model representing stepwise conversion of the above reduction has been developed and the probable rate controlling steps, for different reactions, have been identified.

Synthesis and characterization of trimethylplatinum(IV) complexes with (2-dimethylaminoethyl)organochalcogenides (Me2NCH2CH2ER; E = S, Se, Te). X-ray crystal structure of [PtMe3Br(Me2NCH2CH2SC6H4Me-4)]

Trimethylplatinum(IV) complexes of the type [PtMe 3 X(Me 2 NCH 2 CH 2 ER)] (X = Cl, Br, I; ER = SBu t , SC 6 H 4 Me-4, SPh, SePh, TePh) have been prepared and characterized by elemental analysis and NMR ( 1 H and 13 C) spectral data. The structure of [PtMe 3 Br(Me 2 NCH 2 CH 2 SC 6 H 4 Me-4)] has been determined by single-crystal X-ray diffraction. The central platinum atom is coordinated by three fac -methyl groups and nitrogen, sulphur and bromine atoms. The five-membered chelate ring is non-planar.

Synthesis and characterization of trimethylplatinum(IV) complexes with diphenyldithiophosphinic acid. Crystal and molecular structures of [PtMe3(SSPPh2]2 and [PtMe3(py)(SSPPh2)]☆

Abstract The preparation and characterization of trimethylplatinum(IV) diphenyldithiophosphinates of the type [PtMe 3 (SSPPh 2 )] 2 and [PtMe 3 (L)(SSPPh 2 )](L = mono- or bi-dentate neutral donor ligands) have been reported. On the basis of NMR data ( 1 H, 31 P, 195 Pt), stereochemistry of these complexes has been discussed. The neutral donor ligands cleave the sulphur bridges of the dimeric complex [PtMe 3 (SSPPh)] 2 to give mononuclear complexes. Crystal structures of two compounds [PtMe 3 (SSPPh)] 2 and [PtMe 3 (py)(SSPPh 2 )] have been reported. In the former complex, the dithio ligand acts in a cheating tridentate mode while in the latter complex it is symmetrically chelated.

Synthesis and structure of bis(2-N, N-dimethylamioethyl-selenolato)zinc and its transformation to ZnSe

Abstract The air-stable compound [Zn(SeCH2CH2NMe2)2] (1) as prepared from Zn(OAc)2·2H2O and 2 equiv. of NaSeCH2CH2NMe2 contains monomeric molecules with a characteristically distorted tetrahedral zinc atom coordinated to two selenium and two nitrogen atoms. On thermolysis 1 yields ZnSe which was characterized by XRD.

Synthesis and characterization of organoplatinum(II) dithiolate complexes of the type [PtAr(par|S-S)(PMePh2)]

Abstract The reaction of [pt 2 Ar 2 (μ-Cl) 2 (PMePh 2 ) 2 ] with sodium, potassium or ammonium salts of the dithio acids ( par|S-S ) affords mononuclear complexes of the type [PtAr( par|S S )(PMePh 2 )] (where Ar  Ph, C 6 H 4 Me-4 (tol); par|S S  SSCOEt, SSCNR 2 (R  Me or Et), SSPR 2 (R  OEt, O n Pr, O i Pr, O i Bu, O s Bu, Ph)). The latter complexes were characterized by elemental analysis and nuclear magnetic resonance (NMR) ( 1 H and 31 P) data. These new complexes are inert to excess triphenylphosphine at room temperature.

Recovery of uranium from fluoride matrix by solid state reaction routes

Abstract A simple method is developed for the separation and recovery of uranium in a CaF2 and MgF2 matrix, employing a solid state reaction route, heating the uranium slag-composition mixture with (NH4)2SO4. Reactions of a synthetic slag-composition mixture with (NH4)2SO4 above 350 °C formed sulfate compounds of uranium, calcium and magnesium. The sulfates of uranium were separated by dissolving in dilute acid. Reactions were monitored by TG-DTA analysis. Products formed at different temperatures were characterised by X-ray powder diffraction. Quantitative analysis of the products was achieved using redox titrimetry. By this method about 95% of the uranium present could be recovered from synthetic mixtures.

Synthesis and characterization of methylplatinum(II)O,O′-dialkyl dithiophosphates. Crystal structure of [PtMe{S2P(OPri)2}(AsPh3)]

Methylplatinum(II)O,O′-dialkyl dithiophosphates of the type [PtMe{S2P(OR)2}L] and [PtMe{S2P(OR)2}(L–L)][R = Et or Pri; L = PPh3, P(C6H4Me-p)3, P(OPh)3 or AsPh3; L–L = Ph2PCH2CH2PPh2 or Ph2PCH2CH2AsPh2] have been synthesized. They were characterized by elemental analyses and NMR (1H and 31P) data. A single-crystal X-ray structure determination of [PtMe{S2P(OPri)2}(AsPh3)] has established a chelated dithiophosphate ligand moiety. The four-membered metallacyclic PtS2P ring is planar.

Studies on the dissolution behaviour of ThO2 and (U,Th)O2 by a solid state reaction method

Summary A simple and fast method for the dissolution of sintered ThO2 and (U,Th)O2 was developed. The products formed when these oxides were fused with ammonium sulphate at various temperatures were found to be readily soluble in dilute nitric acid. Among all the products obtained at various temperatures, (NH4)2 Th (SO4)3 and (NH4)2(Ux,Th1-x)(SO4)3, obtained at 365 °C, were found highly soluble (>99%). After dissolution thorium was separated selectively by oxalate precipitation method. More than 95% of uranium was recovered from the solution by ammonium diuranate precipitation method. The products formed at different temperatures were characterised by X-ray, thermal and chemical analysis techniques.

Preparation and characterization of O, O′-dialkldithiophosphate complexes of methylplatinum(II)

Abstract The reaction of [PtMe(X)(COD)] (X = Cl, I) with 1 mole equivalent of NH 4 SS(OR′) 2 gave [{Pt(Me)SSP(OR′) 2 } 2 COD] (R′ = Et or Pr i ). The latter complexes on treatment with tertiary phosphines afforded [Pt(Me){SSP(OR′) 2 } (PR 3 )] (R= 4-MeC 6 H 6 , 2-MeC 6 H 4 or (2, 4, 6-MeO) 3 C 6 H 2 ). All the complexes were characterized by elemental analysis, and NMR data.

Synthesis and characterization of methylpalladium(II) dithiolate complexes of the type [PdMe(S⌢S)(ER3)] (S⌢S = S2CNR 2, S2COEt, S2P(OR)2, S2 PPh2; ER3 = PMePh2, PPh3, AsPh3)

Methylpalladium(II) dithiolate complexes of the type [PdMe(S⌢S)(ER3] (S⌢S = S2 CNR2 (R = Me or Et), S2COEt, S2P(OR)2 (R = Et, nPr, iPr), S2PPh2; ER3 = PMePh2, PPh3, AsPh3) have been synthesized by the reaction of [Pd2Me2(μ-Cl)2(PMePh2)2] with sodium/potassium/ammonium salts of the dithio acid or by treatment of [PdMeCl(cod)] with ER3 followed by sodium/potassium/ammonium salts of the dithio ligand. All the complexes were characterized by elemental analysis, IR and nuclear magnetic resonance (1H, 31P) data.