Veeranna Yempally

• PhD Chemistry
• Texas A&M University at Qatar

Present work deals with the synthesis, characterization and biological investigation of Schiff base ((E)N'(2,3-dihydroxybenzylidene)isonicotinohydrazide (L)) and its diorganotin(IV) complexes (R2SnL, diphenyltin(IV) complex R = Ph (1), dimethyltin(IV) complex R = Me(2))by experimental and theoretical approach. All the complexes were characterized b...

Ethylene dimerization is an efficient industrial chemical process to produce 1‐butene, with demanding selectivity and activity requirements on new catalytic systems. Herein, a series of monodentate phosphinoamine‐nickel complexes immobilized on UiO‐66 are described for ethylene dimerization. These catalysts display extensive molecular tunability of...

Further development in the area of medicinal chemistry requires facile and atom-economical C–N bond formation from readily accessible precursors using recyclable and reusable catalysts with low process toxicity. In this work, direct N-alkylation of amines with alcohols is performed with a series of Ir–phosphine-functionalized metal–organic framewor...

A novel heterogeneous catalyst Fe3O4@SB@Cu that contains a copper(II) Schiff base complex covalently immobilised on Fe3O4 nanoparticles was synthesised. The prepared catalyst is well characterised by FTIR spectroscopy, UV–Visible spectroscopy, FE-SEM, TEM, VSM analysis, EDX, XRD analysis, TGA, CV technique, XPS and PL studies to confirm its structu...

The reduction of nitroarenes to aromatic amines is one of the potential pathways to remediate the hazardous impact of toxic nitroarenes on the aquatic environment. Aromatic amines obtained from the reduction of nitroaromatics are not only less toxic than nitroaromatics but also act as important intermediates in the synthesis of dyes, drugs, pigment...

In the present study, modified Fe 3 O 4 nanoparticles were fabricated by surface coating with tryptophan and Iridium by co-precipitation method to afford Fe 3 O 4 @trp@Ir magnetic nanoparticles. As-prepared Fe 3 O 4 @trp@Ir nanoparticles are environmentally benign efficient catalysts for reducing organic pollutants such as 4-nitrophenol (4-NP), 4-n...

The present study aims to control the particle size and morphology by surface modification of Fe3O4nanoparticles for the best use in catalytic performance. Fe3O4nanoparticles were coated with Schiff base and post modified with dimethyl-tin moiety to yield Fe3O4@[email protected] magnetic nanoparticles. The fully characterized nanoparticles were emp...

Novel bimetallic systems with Re and Sn metals, containing Schiff base linker were designed and explored for their cooperative effect in the catalysis. ReSn bimetallic complexes were prepared by adopting a two-step synthesis procedure, which includes covalent binding of Sn with the Schiff base and then with the Re(CO)5Br. The Schiff base, (E)- N’-(...

This paper describes the catalytic activity of air stable and easy to handle manganese complexes towards the hydrosilylation of aldehydes. These catalysts incorporate a bulky diazabutadiene ligand and exhibit good functional group tolerance and chemoselectivity in the hydrosilylation of aldehydes, utilizing primary silanes as the reducing agent. Th...

The spectrophotometric characteristics of the solid charge-transfer molecular complexes (CT) formed in the reaction of the electron donor 2-amino-6-methylpyridine (2A6MPy) with the p-acceptors tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) and 2,4,4,6-tetrabromo-2,5- cyclohexadienone (TBCHD) have been studied in chlorofo...

The photochemistry of two Mn(bpy)(CO)3X complexes (X = PhCC(-), Br(-)) has been studied in the coordinating solvents THF (terahydrofuran) and MeCN (acetonitrile) employing time-resolved infrared spectroscopy. The two complexes are found to exhibit strikingly different photoreactivities and solvent dependencies. In MeCN, photolysis of 1-(CO)(Br) [1...

A palladium-catalyzed multicomponent method for the synthesis of beta-lactams from imines, aryl halides, and CO has been developed. This transformation proceeds via two tandem catalytic carbonylation reactions mediated by Pd(PtBu3)2, and provides a route to prepare these products from five separate reagents. A diverse range of polysubstituted beta-...

The reaction of Pt(COD)2 with one equivalent of tri-tert-butylstannane, Bu(t)3SnH, at room temperature yields Pt(SnBu(t)3)(COD)(H)(3) in quantitative yield. In the presence of excess Bu(t)3SnH, the reaction goes further, yielding the dinuclear bridging stannylene complex [Pt(SnBu(t)3)(μ-SnBu(t)2)(H)2]2 (4). The dinuclear complex 4 reacts rapidly an...

Dissolution of M(CO)3(Br)(L(Ar)) [L(Ar) = (2,6-Cl2-C6H3-NCMe)2CH2] in either acetonitrile [M = Mn, Re] or benzonitrile (M = Re) results in C-C coupling of the nitrile to the diimine ligand. When reacted with acetonitrile, the intermediate adduct [M(CO)3(NCCH3)(L(Ar))]Br forms and undergoes an intramolecular C-C coupling reaction between the nitrile...

We describe herein a modular nickel-catalyzed synthesis of isoindolinones from imines, aryl iodides, and CO. This reaction is catalyzed by Ni(1,5-cyclooctadiene)2 in concert with chloride salts and postulated to proceed via a tandem nickel-catalyzed carbonylation to form N-acyl iminium chloride salts, followed by a spontaneous nickel-catalyzed cycl...

The complex Pt(SnBu(t)3)2(CNBu(t))2(H)2, 1, was obtained from the reaction of Pt(COD)2 and Bu(t)3SnH, followed by addition of CNBu(t). The two hydride ligands in 1 can be eliminated, both in solution and in the solid state, to yield Pt(SnBu(t)3)2(CNBu(t))2, 2. Addition of hydrogen to 2 at room temperature in solution and in the solid state regenera...

Photolysis of CpRe(CO)3 in the presence of dichloromethane results in the initial formation of the CpRe(CO)2(ClCH2Cl) complex followed by insertion of the metal into the C-Cl bond. The activation enthalpy is determined to be 20.4 kcal/mol, and with the assistance of DFT calculations, a radical mechanism is proposed for the oxidative addition reacti...

The manganese tricarbonyl complex fac-Mn(Br)(CO)3((i)Pr2Ph-DAB) (1) [(i)Pr2Ph-DAB = (N,N'-bis(2,6-di-isopropylphenyl)-1,4-diaza-1,3-butadiene)] was synthesized from the reaction of Mn(CO)5Br with the sterically encumbered DAB ligand. Compound 1 exhibits rapid CO release under low power visible light irradiation (560 nm) suggesting its possible use...

The displacement of a CO ligand from an unusually labile rhenium carbonyl complex containing a bidentate carboxyaldehyde pyrrolyl ligand by PPh(3) and pyridine has been investigated. The reaction is found to proceed by an associative, preequilibrium mechanism. Theoretical calculations support the experimental data and provide a complete energetic p...

The reaction of Fe2(CO)9 and Bu 3tSnH yielded the bimetallic cluster complexes Fe2(μ-SnBu 2t)2(CO)8, 1, and Fe4(μ4-Sn)(μ-SnBu 2t)2(CO)16, 3. Compound 3 contains two Fe2(CO)8(μ-SnBu 2t) groups held together by a central quadruply bridging tin atom, giving an overall bow-tie structure for the one tin and four iron atoms. Refluxing compound 1 in tolue...

Cluster-derived Ru(x)Pt(y)Sn(z) nanoparticles are active catalysts in the hydrogenation of nitrobenzene. The nature of the active sites has been elucidated by FTIR spectroscopy using CO and NO as probe molecules. A new metal carbonyl cluster precursor, Pt(2)Ru(2)(SnBu(t)(3))(2)(CO)(9)(μ-H)(2), has been synthesized to obtain a Ru(2)Pt(2)Sn(2)/SiO(2)...

The bimetallic NiSn2 complex Ni(SnBu3t)2(CO)3, 1, was obtained from the reaction of Ni(COD)2 and Bu3tSnH and CO. The reaction of Co2(CO)8 and Bu3tSnH afforded the bimetallic Co–Sn complex Co(SnBu3t)(CO)4, 3. Compound 3 was also obtained from the reaction of Co4(CO)12 and Bu3tSnH but in a lower yield. Both compounds 1 and 3 were characterized by sin...

The new platinum complex Pt(Sn(t)Bu(3))(2)(CN(t)Bu)(2)(H)(2), 1, was obtained in 32% yield from the reaction of Pt(COD)(2) with (t)Bu(3)SnH and CN(t)Bu at room temperature. Compound 1 is a mononuclear 18 electron platinum complex in an octahedral geometry which contains two Sn(t)Bu(3)'s, two CN(t)Bu's, and two hydride ligands. The two hydride ligan...

The bimetallic cluster complex Fe2(μ-SnBu2t)2(CO)8, 1, selectively activates the benzylic C–H bond in solvent toluene at reflux conditions to afford the complex Fe2[μ-SnBut(CH2Ph)]2(CO)8, 3, where two of the But groups in 1 have been replaced with benzyl groups. Similarly 1 also activates the benzylic C–H bond in solvent m-xylene to yield complexes...

The new bimetallic Fe–Ni carbide containing cluster complex, Fe4Ni(Cp)2(CO)10(μ5-C), 4 was afforded by metal–metal exchange and metal cluster rearrangement processes in the reaction of Fe5(μ5-C)(CO)15, 1, with NiCp2 at 80 °C. A minor product Fe5(Cp)2(CO)10(μ5-C), 5, was also obtained from this reaction which contains no nickel and is a di-Cp substi...