Boere, Rene

Permanent URI for this collection

https://opus.uleth.ca/handle/10133/3778

Browse

Browsing Boere, Rene by Author "Chivers, Tristram"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Electrochemical and chemical reduction of disulfur dinitride: formation of [S4N4], EPR spectroscopic characterization of the [S2N2H]• radical and X-ray structure of [Na(15 crown-5)][S3N3]
    (ACS Publications, 2009) Roemmele, Tracey L.; Konu, Jari; Boeré, René T.; Chivers, Tristram
    Voltammetric studies of S2N2 employing both cyclic voltammetry (CV) and rotating disc electrode (RDE) methods on GC electrodes at RT revealed two irreversible reduction processes at ca. −1.4 V and −2.2 V in CH3CN, CH2Cl2 and THF (vs. ferrocene) and no observable oxidation processes up to the solvent limit when the scan is initially anodic. However, after cycling the potential through −1.4 V, two new couples appear near −0.3 V and −1.0 V due to [S3N3]−/0 and [S4N4]−/0 respectively. The diffusion coefficient D for S2N2 was determined to be 9.13 × 10−6 cm2 s−1 in CH2Cl2 and 7.65 × 10−6 cm2 s−1 in CH3CN. Digital modeling of CVs fits well to a mechanism in which [S2N2]−• couples rapidly with S2N2 to form [S4N4]−•, which then decomposes to [S3N3]−. In situ EPR spectroelectrochemical studies of S2N2 in both CH2Cl2 and CH3CN resulted in the detection of strong EPR signals from [S4N4]−• when electrolysis is conducted at −1.4 V; at more negative voltages, spectra from transient adsorbed radicals are observed. In moist solvent or with added HBF4, a longer-lived spectrum is obtained due to the neutral radical [S2N2H]•, identified by simulation of the EPR spectrum and DFT calculations. The chemical reduction of S2N2 with Na[C10H8] or Na[Ph2CO] produces [Na(15-crown5)][S3N3], while reduction with cobaltocene gives [Cp2Co][S3N3]. The X-ray structure of the former reveals a strong interaction (Na···N = 2.388(5) Å) between the crown ether-encapsulated Na+ cation and one of the nitrogen atoms of the essentially planar six-membered cyclic anion [S3N3]−.
  • Thumbnail Image
    Item
    Preparation and x-ray structure of 4-N,N'-bis(trimethylsilyl)- amino-3,5-diisopropylphenylselenium trichloride
    (Verlag der Zeitschrift für Naturforschung, 1999) Maaninen, Arto; Boeré, René T.; Chivers, Tristram; Parvez, Masood
    The reaction of SeCU or SeCF with /V,/V’-bis(trimethylsilyl)-2,6-diisopropylaniline occurs not at the nitrogen atom but by electrophilic aromatic substitution at C-4 of the phenyl ring to give [(CH3)3Si]2NC6H2('Pr:)SeCl3, which crystallizes as the chloro-bridged dimer in the triclinic system, space group Pi, a - 10.2598(17), b = 13.665(3), c = 9.7838(10) A, a = 90.056(13), ß = 102.439(11), 7 = 70.922(14)°, V = 1262.3(4) A \Z = 1. The dimer contains an essentially planar CUSe^-Cl^SeCU unit, with trans apical (Me3SihNC6H2('Pr)2 groups, resulting in approximately square pyramidal geometry at Se. The bridging Se-Cl distances are unequal at 2.587(2) and 2.749(2) A.