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NMR and XPS Studies of Some Diselenocarbamates. Bond Switch in Bis(dimethylselenocarbamoyl) Triselenide

1986; Oxford University Press; Volume: 59; Issue: 6 Linguagem: Inglês

10.1246/bcsj.59.1741

1348-0634

Keiji Kobayashi, Hideyuki Tukada, Kôichi Kikuchi, Isao Ikemoto,

Molecular spectroscopy and chirality

Abstract The hindered rotation about the C–N bond in dimethyldiselenocarbamates Me2N–CSe–SeR has been investigated by variable temperature NMR spectroscopy. The barrier to the rotation was almost independent of the partial structure of R (R=–Me, –CSe–NMe2), being 19 kcal mol−1* at around 93 °C. However, for bis(dimethylselenocarbamoyl) triselenide (R=–Se–Se–CSe–NMe2) (1), no splitting of N-methyl signals was observed in the 1H and 13C NMR spectra at subambient temperature. The equivalence of the methyl groups is discussed in terms of the bond switch between C=Se and C–Se moieties. The existence of the bond switch in 1 was also suggested by the XPS studies; the binding energy of the four selenium atoms was found to lie between those of C=Se and –Se–types of the selenium atoms, indicating that 1 takes an intramolecular coordination structure rather than a linear triselenide structure in the solid state, thereby facilitates the bond switch in solution.