ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    facet.materialart.
    Unknown
    Observation of alkaline earth complexes M(CO)8 (M = Ca, Sr, or Ba) that mimic transition metals (2018)
    American Association for the Advancement of Science (AAAS)
    In: Science
    Details
    Publication Date: 2018-08-31
    Description: The alkaline earth metals calcium (Ca), strontium (Sr), and barium (Ba) typically engage in chemical bonding as classical main-group elements through their n s and n p valence orbitals, where n is the principal quantum number. Here we report the isolation and spectroscopic characterization of eight-coordinate carbonyl complexes M(CO) 8 (where M = Ca, Sr, or Ba) in a low-temperature neon matrix. Analysis of the electronic structure of these cubic O h -symmetric complexes reveals that the metal–carbon monoxide (CO) bonds arise mainly from [M(d )] -〉 (CO) 8 backdonation, which explains the strong observed red shift of the C-O stretching frequencies. The corresponding radical cation complexes were also prepared in gas phase and characterized by mass-selected infrared photodissociation spectroscopy, confirming adherence to the 18-electron rule more conventionally associated with transition metal chemistry.
    Keywords: Chemistry
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    Electronic Resource
    Electronic Resource
    Pervaporation separation of ethanol-water mixtures using crosslinked blended polyacrylic acid (PAA)-nylon 66 membranes (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2133-2145 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The pervaporation separation of ethanol-water mixtures was carried out through a series of ionically crosslinked polyacrylic acid (PAA)-nylon 66 blended membranes crosslinked to varying degrees in aluminum nitrate solution. Optimum pervaporation results were obtained from crosslinked blends containing 75 wt % nylon 66 and 25 wt % PAA. The optimum crosslinking time was found to be between 30 and 40 h. The optimum operating temperatures of the pervaporation runs were found to be 2-3°C below the boiling points when the highest permeation flux reached 857.6 (g/m2 h) and the best separation factors (water/ethanol) were 10.1.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410918
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Radiolysis of poly(acetaldehyde-co-chloral): A positive E-beam resist (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 27 (1989), S. 1571-1588 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acetaldehyde and chloral were copolymerized using triethyl aluminum catalyst. The copolymer (ACC) obtained with equimolar monomer feed is not alternating in structure as it was once thought to be; it is comprised of two fractions differing in MW and composition. ACC has good thermal stability which is further improved by endcapping. Radiolysis in vacuo caused depolymerization with a G(M) value (number of monomers produced per 100 eV) of about 4000 to 80% completion. The G(S) value for chain scission is 1.9. These processes are effectively inhibited by benzoquinone. Oxygen markedly increases G(M) to ca. 18,000 and 〉 97% completion. Addition of tetrabutyl ammonium salt or tetramethyl urea has no effect on the depolymerization, whereas the addition of di-t-butyl-p-cresol causes an induction period after which normal unzipping ensues. Even UV photolysis of ACC in the presence of oxygen produces monomer with a quantum yield of 1.7, but very little photolysis occurs in the absence of oxygen. Gamma radiolysis sensitized by (C6H5)2IPF6 has G(M) value of 32,700. These results are very similar to the radiolysis and photolysis of the homopolymer of monochloroacetaldehyde and reinforce the mechanisms proposed for them. The E-beam sensitivity of ACC is about 3 × 10-6 C cm-2.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1989.080270509
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Strategies for supercritical CO2 fractionation of polydimethylsiloxane (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 773-778 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The fractionation of polydimethylsiloxane (PDMS) using supercritical CO2 was studied to determine the parameters of pressure and temperature required to separate specific molecular weights. On a laboratory scale, we show that this fractionation method can quickly provide gram quantities of the polymer with a polydispersity of around 1.2 for molecular weights in excess of 200 kg/mol. This technique has obvious applications in the preparation of PDMS for surface-related uses. © 1995 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550514
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...