Gasförmiges „H3PS2”︁ – Erzeugung und Charakterisierung

Gaseous “H₃PS₂” – Generation and Characterization Double alkene elimination from molecular ions (El: 70 eV) of dialkyldithiophosphinic acids R₂P(S)SH (R: Et, nPr, nBu) leads to radical cations of composition [H₃PS₂]^+. (m/z 98). By analysis of the collisional activation (CA) mass spectrum and using thermochemical data it was shown that [H₃PS₂]^+. exists as a mixture of structures [H? P(SH)₂]^+. and [HSP? SH₂]^+. containing tri- or dicoordinated phosphorus, respectively. No structure corresponding to ionized dithiophosphinic acid H₂P(S)SH was observed. Via neutralization reionization mass spectrometry (NRMS) neutral molecules ?H₃PS₂”? were obtained which proved to be stable in the dilute gas phase and most probably are of structure H? P(SH)₂. Experimental findings are in accordance with the results of semiempirical MO-calculations (MNDO).     

Synthesis,purification, and characterization of “perfect” star polymers via “Click” coupling

The copper (I)‐catalyzed azide‐alkyne cycloaddition “click” reaction was successfully applied to prepare well‐defined 3, 6, and 12‐arms polystyrene and polyethylene glycol stars. This study focused particularly on making “perfect” star polymers with an exact number of arms, as well as developing techniques for their purification. Various methods of characterization confirmed the star polymers high purity, and the structural uniformity of the generated star polymers. In particular, matrix‐assisted laser desorption ionization‐time‐of‐flight mass spectrometry revealed the quantitative transformation of the end groups on the linear polymer precursors and confirmed their quantitative coupling to the dendritic cores to yield star polymers with an exact number of arms. In addition to preparing well‐defined polystyrene and poly(ethylene glycol)homopolymer stars, this technique was also successfully applied to amphiphilic, PCL‐b‐PEG star polymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Beryllepin,C6H6Be,and “Beryllium‐Inserted Benzenes,” C6H6Ben,n = 2–6: A Density Functional Computational Investigation

The seven‐membered beryllium‐containing heterocycle beryllepin, C₆H₆Be, has been examined computationally at the B3LYP/6‐311++G** density functional level of theory. Beryllepin is best described as a planar singlet heterocyclic conjugated triene with marginal aromatic character containing a C–Be–C moiety forced to be nonlinear (∠C‐Be‐C = 146.25°) by the cyclic constraints of the seven‐membered ring. The molecule can be considered to be derived from a benzene‐like system in which a neutral beryllium atom has been inserted between two adjacent carbon atoms. The 11 other possible “beryllium‐inserted benzenes,” C₆H₆Be_n, n = 2–6, have also been investigated. Only two of these heterocyclic systems, the eight‐membered 1,4‐diberyllocin and the nine‐membered 1,4,7‐triberyllonin, were found to be stable, singlet‐ground‐state systems, albeit with little aromatic character. Of the remaining nine beryllium‐inserted benzenes, with the exception of the 11‐membered ring containing five beryllium atoms and the 12‐membered ring containing six beryllium atoms, which were calculated to exist as a ground state pentet and septet, respectively, all were calculated to be ground state triplet systems.