1,2-Dichalcogenine: einfache Synthese von 1,2-Diseleninen, 1,2-Dithiinen und 2-Selenathiin

Abstract

Durch Ringöffnung des Titanacyclopentadiens 1 mit (SCN)2 oder (SeCN)2 und anschließende Bis(thiocyanat)‐ bzw. Bis(selenocyanat)‐Cyclisierung erhält man das 1,2‐Dithiin 2 a bzw. das 1,2‐Diselenin 2 b. Mit S2Cl2 kann 2 a direkt aus 1 hergestellt werden. Das unsubstituierte 1,2‐Diselenin konnte durch Reaktion von PhCH2SeNa mit 1,4‐Bis(trimethylsilyl)‐1,3‐butadiin sowie anschließende reduktive Abspaltung der Benzylgruppen und Oxidation erhalten werden. 2‐Selenathiin wurde analog synthetisiert, wobei allerdings ein Gemisch aus PhCH2SeNa und PhCH2SNa verwendet wurde.

MP2 calculation of 77Se NMR chemical shifts taking into account relativistic corrections

“…Presented in Table are the results of the benchmark calculations of 77 Se NMR chemical shifts of a representative series of diverse organoselenium open‐chain and heterocyclic compounds 1–17 against available experimental data taken from different sources for 1 , 2 , 3 and 12 , 4 , 5 , 6 , 7 , 8 and 9 , 10 , 11 , 13 , 14 , 15 , 16 , and 17 . Calculated at the GIAO‐MP2/dyall.av4z level (scheme C ), selenium isotropic absolute shielding constants were converted into 77 Se NMR chemical shifts scale referenced to dimethyl selenide ( δ , parts per million) as recommended by the International Union of Pure and Applied Chemistry using the equation δ = ( σ Me2Se − σ )/(1 − 10 −6 σ Me2Se ), where σ and σ Me2Se are the 77 Se NMR isotropic absolute shielding constants of, accordingly, the compound under consideration and dimethyl selenide calculated at the same level of theory.…”

Four‐component relativistic DFT calculations of 77Se NMR chemical shifts: A gateway to a reliable computational scheme for the medium‐sized organoselenium molecules

“…In all calculations, we used the locally dense basis set scheme (see Methods), well approved in our previous work . Calculated 77 Se NMR chemical shifts are benchmarked against their experimental values measured in nonpolar solvents (CDCL 3 , CD 2 Cl 2 , CCl 4 ) elsewhere for compounds 2 , 3, 4, 5, 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , and 18 . The relative performance of seven tested functionals together with RPA scheme to reproduce experimental values of 77 Se NMR chemical shifts in the series of 2–18 is demonstrated in Figure showing MAEs of the calculated values against experiment.…”