177,036 research outputs found
Synthesis and X-ray crystal structure of the novel organotin dication [n-Bu2Sn(H2O)4]2+: A lamellar layered structure assisted by intermolecular hydrogen bonding
No full textThe reaction of n-Bu2SnO with 2,5-dimethylbenzenesulfonic acid affords the stable monomeric tin complex [n-Bu2Sn(H2O)4]2+[2,5-Me2 -C6H3SO3]2-. The solid-state structure of the molecule reveals that the hydrogen-bonding interaction between the coordinated water and the sulfonate anion moieties leads to an unprecedented two-dimensional layered structure with a planar array of tin atoms. Further, the Lewis acidic dication complex is an extremely good catalyst for acylation of alcohols and phenols
Synthesis, Structure and Reactivity of Hydrated and Dehydrated Organotin Cations
No full textMonomeric organotin dications {[nBu2Sn(H2O)4]2+·2C6H5SO3-} and {[nBu2Sn(H2O)4]2+·1,5-C10H6(SO3-)2} have been synthesized by the reaction of [nBu2SnO]n and the corresponding arylsulfonic acid. Dodecanuclear organooxotin macrocations {[(nBuSn)12(μ 3-O)14(μ 2-OH)6]2+·2RSO3-} (R = C6H5; 2,5-Me2C6H3) have been synthesized by the reaction of nBuSn(O)(OH) and the corresponding arylsulfonic acid. The X-ray crystal structure of one of the dodecanuclear cages is reported. These organotin cations have been shown to be effective catalysts in acetylation and transacetylation reactions
N-Bonded Monosilanols: Synthesis and Characterization of ArN(SiMe3)SiMe2Cl and ArN(SiMe3)SiMe2OH (Ar = C6H5, 2,6-Me2C6H3, 2,6-iPr2C6H3)
No full textBy the use of aniline and the sterically hindered aromatic
primary amines, 2,6-Me2C6H3NH2 and 2,6-iPr2C6H3NH2, Nbonded
monochlorosilanes, ArN(SiMe3)SiMe2Cl [Ar = C6H5
(1a), Ar = 2,6-Me2C6H3 (1b) and Ar = 2,6-iPr2C6H3 (1c)] have
been prepared by a sequential deprotonation at the nitrogen
followed by reaction with silyl chlorides. Hydrolysis of the Nbonded
monochlorosilanes afforded the N-bonded monosilanols
ArN(SiMe3)SiMe2OH [Ar = C6H5 (2a), Ar = 2,6-Me2C6H3 (2b) and Ar = 2,6-iPr2C6H3 (2c)]. The X-ray crystal
structure of 1c reveals a positional disorder of the Cl and CH3
substituents on silicon. The X-ray crystal structure of 2c
shows that it is involved in an intermolecular O–H···O hydrogen
bonding in the solid state to afford a dimeric structure
containing the O2H2 ring
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Solventless Reactions for the Synthesis of Organotin Clusters and Cages
No full textOrganotin clusters and cages have been synthesized in quantitative yields by using a benign solventless synthetic methodology. Using this method a variety of structural forms, which include the drum, O-capped cluster, tetranuclear oxo cage, discrete, and polymeric compounds, have been synthesized. All these compounds (1-11) have been characterized by spectroscopic and analytical techniques. The new compounds, which include the hexameric drum [n-BuSn(O)OCOAd]6 (Ad = adamantyl) 9, a triorganotin-based discrete structure Ph3SnO2C-C6-H 22,4,6-Me3 (10), and a polymer Ph3SnOSO 2-C6H3-2,5-Me2 (11), have been characterized by single-crystal X-ray crystallography
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Letter from R. R. Zellick, Assistant Trust Officer, Anglo California National Bank of San Francisco, to Joseph R. Goodman, October 2, 1942
No full textLetter from R. R. Zellick, Assistant Trust Officer at The Anglo California National Bank of San Francisco, to Joseph R. Goodman, regarding property owned by Dave Tatsuno. Zellick mentions a dispute between current tenants and Tatsuno, and that Tatsuno has asked Goodman to help locate trustworthy tenants.Personal correspondence, organizational records, government documents, publications, and other papers created or collected by Joseph R. Goodman documenting the forced removal and incarceration of Japanese Americans during World War II, as well as organized resistance to incarceration. Included in the collection are records of the Japanese Young Men's Christian Association and the Japanese American Citizens' League in San Francisco, including papers of the Japanese YMCA's executive secretary Lincoln Kanai; Sakai family papers; Goodman's correspondence to and from Japanese American incarcerees, organizations opposing forced removal and incarceration of Japanese Americans, the War Relocation Authority, and others; publications, photographs, and ephemera from the Topaz Relocation Center, where Goodman taught high school; War Relocation Authority records and publications; and newspaper clippings, pamphlets, and reports about forced removal and incarceration created by various government, religious, and civic organizations, in California and nationwide
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
