Abstract
A series of isoselenocyanates, SeCNR, spanning over a variety of organic residues in terms of steric encumbrance and electronic effects, was synthesized by reactions of corresponding isocyanides with elemental selenium. The residues range from tertiary butyl ((t)Bu), phenyl (Ph), 2,4,6-trimethylphenyl (Mesityl), 2,6-diisopropylphenyl ((i-Prop2)Ph), 2,6-di(2,4,6-trimethylphenyl)phenyl (Ar(Mes2)), 2,6-di(2,6-diisopropylphenyl)phenyl (Ar(Dipp2)), 2,6-di(2,4,6-triisopropylphenyl)phenyl (Ar(Tripp2)), and 4-fluorophenyl (PhF) to 2,6-di{3,5-di(trifluoromethyl)phenyl}4-fluorophenyl (p-FAr(DarF2)). They were formed as crystalline solids or viscous oils in medium to good yields, which recommends this synthetic approach as generally suitable. The products were studied by X-ray diffraction and spectroscopic methods, including (77)Se NMR spectroscopy. The influence of the organic substituents on the (77)Se NMR chemical shifts of the isoselenocyanates is in good accordance with DFT-modeled values. Experimental (77)Se-(13)C couplings of 280 Hz could be derived for Se(13)CNAr(Dipp2) prepared from a sample of (13)CNAr(Dipp2) (isotopic enrichment: 99%). A small amount of a selenourea-type product, (i-Prop)(2)NC(Se)NHp-FAr(DarF2), was isolated from a reaction mixture of CNp-FAr(DarF2) with selenium and diisopropylamine as the supporting base, which indicates an influence of the supporting base used for the course of the reaction.