Publications

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTReactivity of an Osmium Silylene Complex toward Chlorocarbons: Promotion of Metal Redox Chemistry by a Silylene Ligand and Relevance to the Mechanism of the Direct ProcessPaulus W. Wanandi, Paul B. Glaser, and T. Don TilleyView Author Information Department of Chemistry University of California at Berkeley Berkeley, California 94720-1460 Cite this: J. Am. Chem. Soc. 2000, 122, 5, 972–973Publication Date (Web):January 21, 2000Publication History Received25 August 1999Published online21 January 2000Published inissue 1 February 2000https://pubs.acs.org/doi/10.1021/ja993089lhttps://doi.org/10.1021/ja993089lrapid-communicationACS PublicationsCopyright © 2000 American Chemical SocietyRequest reuse permissionsArticle Views523Altmetric-Citations56LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Anions,Pharmaceuticals,Reactivity,Silicon,Solutions Get e-Alerts

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Ruthenium-Catalyzed Hydrative Cyclization and [4 + 2] Cycloaddition of Yne-enonesBarry M. Trost, Rebecca E. Brown, and F. Dean TosteView Author Information Department of Chemistry Stanford University Stanford, California 94305-5080 Cite this: J. Am. Chem. Soc. 2000, 122, 24, 5877–5878Publication Date (Web):June 3, 2000Publication History Received28 January 2000Published online3 June 2000Published inissue 1 June 2000https://pubs.acs.org/doi/10.1021/ja000314mhttps://doi.org/10.1021/ja000314mrapid-communicationACS PublicationsCopyright © 2000 American Chemical SocietyRequest reuse permissionsArticle Views1897Altmetric-Citations74LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Cyclization,Hydration,Hydrocarbons,Ketones,Ruthenium Get e-Alerts

Abstract Studies of ancient and active subduction zones are critically important to understanding processes of interplate coupling, crust‐mantle recycling and arc magmatism. Dating subduction metamorphism along prograde and retrograde paths in order to constrain such processes, however, has proved to be extremely difficult. The complex thermal history of subduction systems poses significant challenges to low‐ T geochronometers and subduction‐zone assemblages commonly lack suitable minerals for higher temperature geochronology. Garnet and lawsonite, however, are critical index minerals of high‐ and low‐ T subduction‐zone metamorphism and are well suited to Lu–Hf geochronology. In addition, the closure temperature for Lu–Hf in garnet and lawsonite should be sufficiently high that an age will date mineral crystallization and therefore the timing of subduction zone metamorphism. The relative stability and timing of garnet and lawsonite formation will be controlled by the bulk composition, peak metamorphic conditions and shape of the P – T path experienced by a particular sample. To test the influence of metamorphic conditions and P – T path on Lu–Hf geochronology, garnet and lawsonite‐bearing samples were dated from rocks where lawsonite formed after garnet along a retrograde path, stabilized prior to garnet along a prograde path and formed contemporaneously with garnet. In the Franciscan Complex, the ages of garnet–epidote amphibolite, garnet–epidote blueschist, garnet–lawsonite blueschist and lawsonite blueschist range from c . 166–130 Ma and generally decrease with decreasing metamorphic grade, consistent with previous studies. Garnet–lawsonite blueschist/eclogite formed along an apparent prograde path at Ward Creek records an apparent age of c . 152 Ma. Lower temperature lawsonite blueschist at Ward Creek, however, failed to provide a geologically significant date and likely reflects isotopic disequilibrium at low temperatures. The apparent temperature–time history from Franciscan Complex Lu–Hf ages most likely reflects samples derived from various portions of the subduction zone or that were subducted and metamorphosed at different times in the thermal evolution of the subduction zone. In the Sivrihisar Massif, lawsonite eclogite and garnet–lawsonite blueschist record distinctly different ages of 91.1 ± 1.3 Ma and 83.3 ± 1.8 Ma. The different ages date the timing of high‐ P metamorphism within each protolith and suggest that garnet–lawsonite eclogite metamorphism pre‐dated garnet–lawsonite blueschist metamorphism in these samples by c . 8 Ma. The age of lawsonite eclogite metamorphism extends the timing of high‐ P metamorphism and requires subduction initiation prior to 91 Ma. The results indicate that the Lu–Hf system provides a reliable tool for dating the wide range in P – T conditions of subduction‐zone metamorphism. Lawsonite dating, in particular, provides a reliable method by which to date low‐ T retrograde and prograde metamorphism in the absence of garnet. Lawsonite may not be ideal for geochronology if sufficient garnet coexists in the mineral assemblage, the lawsonite has very low‐ T stability, or if extremely fine‐grained Hf phases such as zircon are present in lawsonite. In poly‐metamorphic assemblages where the pressure and temperature can be estimated for separate garnet and lawsonite sub‐assemblages, the age discrepancy between garnet and lawsonite may provide the ability to quantify the rates of heating or cooling and subduction or exhumation.

In the UK’s 2016 Brexit referendum, young voters were more likely than their elders to support remaining in the European Union. Using half a century of data and new techniques, we find that recent cohorts tend to be more pro‐European than their predecessors, but that voters also become more sceptical towards Europe as they age. Much of the pro‐Europeanism of recent cohorts is associated with greater years of education. We also document large nationwide swings in sentiment that have little to do with age or cohort effects. These time effects are plausibly associated with, inter alia , macroeconomic fluctuations, financial conditions and geopolitical circumstances, but they also could have other sources. They dominate the impact of the estimated age and cohort effects and will crucially determine future UK support for membership in the European Union.

Abstract

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

A series of enantioselective polycyclization reactions, catalyzed by a cationic bisphosphine gold complexes, are described. The polycyclization reactions, which employ an alkyne as an initiating group, begin with a gold-promoted 6-exo-dig cyclization and can be terminated with a variety of nucleophiles including carboxylic acids, phenols, sulfonamides, and electron-rich aryl groups. This method allows for the preparation of up to four bonds in a single operation with excellent diastereo- and enantioselectivity.