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The adsorption properties of Rn on polycrystalline surfaces of the transition metals Cu, Ag, Au, Ni and Pd are investigated experimentally with the help of vacuum thermochromatography. It provides a fast separation of short-lived nuclides of volatile elements on clean metal surfaces.

Research describes a methodology for the dimerization of substituted 2-bromopyridines in the context of formation of stable complexes of transition-metal catalysts in the reactions involving heterocyclic substrates. The electrochemical approach described is based on the combination of the nickel complex catalysis and the sacrificial anode.

This article discusses the homogeneous catalytic oxidation widely employed in chemical and petrochemical industries for the manufacture of oxygenated hydrocarbon compounds. Authors review the developing facet of oxidation chemistry in relation to nonmetal catalysts' efficacy, utility, and benefits in the organic synthesis and draw comparison to the metal based catalysts.

Designed transition metal compounds were used in the surface recognition of a protein, bovine erythrocyte.

Vanadium phthalocyanine and porphyrin complexes, in conjunction with methylaluminoxane (MAO) or EtAl[Cl.sub.2] cocatalyst, have been found to catalyze the homopolymerization of ethene. In addition, the copolymerization of ethene with propene and 1-decene was achieved with the vanadium phthalocyanine complex and MAO. Nickel phthalocyanine complex was also found to catalyze the polymerization of ethene in the presence of MAO. However, only dimerization was observed when EtAlpCl.sub.2] was used as the cocatalyst. Key words: phthalocyanine, porphyrin, polymerization, copolymerization, ethene, propene, 1-decene.

Research discusses the usefulness of covalent metal-organic networks (CMONs) in the understanding of dimensionality controlled by the elements. Results delineate CMON materials containing varied number of metal centers produced from the in situ reduction of vanadium precursors.

Research describes aziridination of olefins using Bromamine-T, in the form of TsN-NaBr, for nitrogen source in reactions catalyzed by copper(I) or copper(II). Data indicate that Bromamine-T is superior to Chloramine-T and copper-halides are the best catalysts.

This paper discusses the chemistry of hydrostannanes in relation to their utility in the synthesis of organotin compounds, distannanes and polystannanes. Research shows that group 4 transition-metals, iron-palladium complexes, catalyze the synthesis of these compounds from hydrostannanes via the dehydrogenative coupling reactions. Mechanastic aspects of the catalysis are presented.

The vinyl stannane intermediates are obtained from the transition-metal-catalyzed hydrostannation of alkynes by the addition of tin hydride stereospecifically. Additionally, allyl- and vinylstannanes can be prepared from hydrostannation of allenes using homogeneous or Pearlman catalysts.

This review describes the addition of silicon-element sigma-bonds to the unsaturated organic molecules using transition-metal catalysts. Data indicate that these additions can occur in regio- and stereoselective manners. Additionally, same mechanistic features may influence other element-element sigma-bonds to react with the unsaturated organic molecules in the presence of transition metals.

Recent advances in the chemistry of transition metal-catalyzed organosulfur compounds containing carbon-sulfur bonds are reviewed here. A description of the novel reactions in this field such as reaction of halides with sulfur-containing compounds, allylic sulfide synthesis, addition of thiols to alkynes, alkenes, and allenes is presented.

The chemistry of transition metal-catalyzed activation of Carbon-X bond to the Carbon-Carbon bond formation is presented. Research shows that under the right conditions, halides like alkyl iodides, undergo cross-coupling, carbonylation, and olefin insertion reactions to give rise to carbon-carbon bond formation.

Compounds other than the conventional organometallic reagents such as allylic, vinylic, and arylmetal compounds have recently been introduced to carbon-carbon bond-forming reactions. Research demonstrates that highly beneficial organometallic compounds can be obtained from the transmetalated organopalladium intermediates.

This review addresses the construction of carbocyclic and heterocyclic compounds using allyl, propargyl, and alkynyl complexes containing transition metals iron(II), molybdenum(II), and tungsten(II). These organometallic compounds are mild nucleophiles and form stable carboniums.

Organic synthesis of cyclohexadiene ligands starting from tricarbonyliron-diene complexes is presented. Recent developments in the methodologies for the synthesis of tricarbonyliron transfer reagents and the catalytic complexation of dienes by the tricarbonyliron together with the asymmetric catalytic complexation of cyclohexa-1,3-dienes are discussed.

The regioselective synthetic approaches to polysubstituted benzenes are carried out by stepwise addition of protected substituents via electrophilic substitution reactions. This review discusses recent advances in this field and focuses on the transition-metal-catalyzed cyclotrimerization and cycloaddition reactions in the regioselective synthesis of polysubstituted benzenes.

This paper discusses the organic synthetic reactions in which olefins with a carbon-carbon unsaturated bond reacts with titanium both at carbanion or transition metal characteristic reactions at tandem. Such reactions lead to the generation of alkene- or alkyne-titanium complexes eventually giving rise to organotitanium complexes.

This review delineates the laws and principles governing radical chemistry and how reagent control is exercised on these reactions. Metal-catalyzed radical reactions using suitable radical precursors generated by the reagent-controlled reactions aid in the transformation of the radical by the addition of carbon-carbon multiple bonds.

Research was conducted to examine the asymmetric Pauson-Khand type cyclization of nitrogen-containing enynes using carbon monoxide and a catalytic amount of (EBTHI)TiMe2. An analysis of the effect of the nitrogen substituent and the concentration of the catalyst on the enantioselectivity of the cyclization was performed. Results provide evidence that (EBTHI)TiMe2 is an effective precatalyst for the asymmetric synthesis of nitrogen-containing bicyclic cyclopentenones.

Transition metal were used to catalyze the ring-opening polymerization (ROP) of silicon-bridged {1}ferrocenophanes. The Pt-catalyzed ROP of Fe(nu-C5H4)(nu-C5Me4)SiMe2 in solution at 25 degrees C entails partial cleavage of the Si-Cp(super H) bond to produce a crystalline poly(ferrocenylsilane) characterized by a regioregular microstructure. On the other hand, thermal ROP of the silicon-bridged {1}-ferrocenophanes takes place through a nonselective cleavage of the Si-Cp(super H) and SiCp(super Me) bonds.

Zeolite analogues that contain transition metals are useful in industrial processes such as catalysis and gas separation. Several new zeolite structural analogues have been synthesized based on cobalt phosphate. The approach used to make zeolite analogues, could be applied to systems with diverse structural types and chemical constructions, and also be used to make structural analogues of other silicate structures.

The absorption and emission spectroscopic properties of divalent zinc chalcogenides doped with Cr, Co, Fe and Ni reveal that Cr2+ ion is a suitable laser ion for mid-IR. Destructive effects of nonradiative decay are absent in the Cr2+ ion which has an emission lifetime of around 8 micro sec. Cr has strong luminescence at room temperature. Laser demonstrations of Cr:ZnS and Cr:ZnSe in a laser-pumped cavity with a CO:MgFe pump laser indicate that the output of both lasers have a peak at 2.35 micrometer and have a maximum slope efficiency of about 20%.

A synthetic methodology for the construction of organic compounds is described. It involves the use of enantioselective transition metal-catalyzed allylic alkylations which may result in carbon-carbon and carbon-heteroatom bond formations. The discussion is limited to reactions which promote nucleophilic displacements on allylic substrates. It includes a description of the pi-allyl stereodynamics of the reactions.

The heat produced during the formation of transition-metal silicides is correlated with the intrinsic Schottky-barrier height obtained from an interface-defect-free model. The previously determined anomalous values reported for the PtSi and IrSi linear correlation are also considered in the model. The transition-metal silicide interfaces are used widely as gate electrodes and Ohmic and Schottky barrier contacts in very large-scale integration. The atomic and the electronic structures at the interface are related to the Schottky-barrier formation at the metal-semiconductor interfaces.

A new approach to activate a carbon-carbon bond in solution has been followed by using the process of activating a simple C-C bond by a mononuclear rhodium complex in a neutral homogeneous medium, because C-C bonds usually do not react when transition metals in solutions are inserted. A metal-hydride complex was used to find if the transition-mental insertion into a C-C bond is possible. Slight heating helped to remove the kinetic barrier which obstructed C-C division. This new approach states that although metal pre-coordination aids C-C activation, it need not be absolutely essential if selective transformation of C-C bonds can be achieved by homogenous activation.

The strength and the mechanism of cleavage of the Co-C bond and the effect of trans-ligands on these properties are studied. The study is said to be a part of a wider analysis of the redox-controlled binding of NO by transition metal complexes.

Research describes synthesis and coordination chemistry of the imino nitroxide raical bearing ligand in combination with platinum(II) and palladium(II) metal ions. Results indicate that while the platinum derivative exhibits ferromagnetic intermolecular interactions, the palladium derivative shows an overall antiferromagnetic behavior.

The biodegradable strong transition metal chelant [S,S] stereoisomer of ethylenediamine disuccinate was investigated for its applicability for the washing extraction of heavy metals from soil, sewage sludge, and harbor sediment. Heavy metals Pb, Zn, Cu, and Cd were extracted from authentically polluted samples by means of an ex situ washing procedure at the laboratory scale. The exposure time necessary to achieve maximum metal extraction from the authentically polluted solids used in this study was longer than that reported elsewhere with solids polluted artificially in the laboratory. Required exposure time was 1 day for the extraction of Pb, 3 days for Zn, and 6 days for Cu, irrespective of solid type. Speed and extent of metal extraction were increased by facilitating mass transfer from the solids to the liquid (e.g., by lowering calcium concentration, increasing temperature, adding fatty acid soap, and most of all, by using intermittent but intense agitation). Slightly alkaline pH was necessary to eliminate the interference by iron. This pH effect as well as observed metal selectivity was explained with a speciation model. It was feasible to achieve 70-90% extraction of Zn, Pb, and Cu from all three solids tested. These extraction efficiencies were equal or superior to those obtained with the benchmark chelants, ethylenediamine tetraacetic acid and nitrilotriacetate, provided extraction time was sufficient.

A study was conducted on the transition metal-catalyzed allylic animation reaction. It reports the first regioselective rhodium-catalyzed allylic animation of a series of unsymmetrical, acyclic, enantiomerically enriched carbonates with the lithium anion of N-tosyl benzylamine to produce secondary allylamines in high yield and with retention of absolute configuration. These intermediates are useful synthons for the synthesis of alpha-amino acids and nitrogen containing heterocycles.

The first-ever palladium-catalyzed alkoxyallylation of activated olefins is presented. The reaction showed that activated olefins can be converted into beta-alkoxy-alpha-allylated adducts in a single stroke under essentially neutral conditions by the intermolecular delivery of RO group. This novel type of transformation is not easily available through conventional organic reaction, but is made possible by transition-metal-catalyzed reaction.

The catalytic generation of the silicon-oxygen double bond from secondary silanols using a transition metal complex is described. The reaction, which is an unprecedented form of catalysis, involves platinum-catalyzed silanol dehydrogenation and proceeds in solution under very mild conditions. Its mechanism, including isolation and structural characterization of a key intermediate by spectroscopy and X-ray diffraction, is reported. It is formally analogous to the catalytic dehydrogenation of alcohols that leads to ketones.

The homogenous transition-metal-catalyzed C-F activation reactions are demonstrated in the selective hydrogenolysis of C6F6 and C6F5H with hydrogen and trimethylphosphine complexes of rhodium as catalysts in the presence of a base. The catalytic cycle of hydrogenolysis incorporates electron-rich hydridorhodium(I) phosphine complexes inducing scission of the C-F bonds.

'even-membered carbocycles are synthesized through a transition of metal-mediated (3 + 2 + 2) cycloaddition, coupling an eta(super 3)-allyl ligand with two alkynes to yield the eta(super 5)-cycloheptadienyl ring system. The eta(super 5)-cycloheptadienyl complex is also formed by the reaction of allyl diphenylacetylene complex with excess 2-butyne.

The degradation of alkyl-substituted thiophene rings are promoted by transition metal centers which act as electrophiles and by reduction to effect the carbon-sulfur (C-S) cleavage reactions. In normal thiophene rings the sequence of reduction followed by protonation cause the scission of the C-S bond. The C-S bond which is less sterically hindered is easily splitted.

The seven-membered ring compounds are effectively synthesized by (5 + 2) cycloadditions of vinylcyclopropanes and alkynes, catalyzed by a transition metal, a homolog of the Diels-Alder reaction. The electronic and steric factors incorporated by the substituents of the alkyne do not influence the cycloaddition process, except for the influence on the volatile product.

The development of a new path for the synthesis of phosphinboranes in chains, rings and macromolecules is discussed. The method involves use of a transition metal and catalyst to produce the phosphorus-boron bonds.