Reactions of an Isolable Dialkylstannylene with Carbon Disulfide and Related Heterocumulenes
2016-04-21T13:06:22Z (GMT) by
The reaction of isolable dialkylstannylene 1 with an excess amount of CS2 produces an isomeric mixture of 3,3′-distanna-2,2′,4,4′-tetrathiabicyclobutylidene 8 and 3,7-distanna-2,4,6,8-tetrathiabicyclo[3.3.0]oct-1(5)-ene 9 with a ratio depending on the reaction conditions. Compounds 8 and 9 are separated by column chromatography and characterized by NMR spectroscopy and X-ray crystallography. Detailed investigation of the reaction has revealed that the initial product is 8, which isomerizes to 9 irreversibly under the catalytic influence of 1 as a Lewis acid. The above view is supported by the theoretical DFT calculations. Treatment of 1 with ArNCO [Ar = 2,6-iPr2C6H3] affords the corresponding carbamoyl(hydroxyl)stannane 11 via the hydrolysis of the corresponding silaaziridinone formed by the [1 + 2] cycloaddition reaction of 1 with the NC double bond of the isocyanate. Stannylene 1 reacts with ArNCS, giving a mixture of complex products, while 1 does not react with CO2.