Reactions of an Isolable Dialkylstannylene with Carbon Disulfide and Related Heterocumulenes
2016-04-21T13:06:28Z (GMT) by
The reaction of isolable dialkylstannylene <b>1</b> with an excess amount of CS<sub>2</sub> produces an isomeric mixture of 3,3′-distanna-2,2′,4,4′-tetrathiabicyclobutylidene <b>8</b> and 3,7-distanna-2,4,6,8-tetrathiabicyclo[3.3.0]oct-1(5)-ene <b>9</b> with a ratio depending on the reaction conditions. Compounds <b>8</b> and <b>9</b> 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 <b>8</b>, which isomerizes to <b>9</b> irreversibly under the catalytic influence of <b>1</b> as a Lewis acid. The above view is supported by the theoretical DFT calculations. Treatment of <b>1</b> with ArNCO [Ar = 2,6-<i>i</i>Pr<sub>2</sub>C<sub>6</sub>H<sub>3</sub>] affords the corresponding carbamoyl(hydroxyl)stannane <b>11</b> via the hydrolysis of the corresponding silaaziridinone formed by the [1 + 2] cycloaddition reaction of <b>1</b> with the NC double bond of the isocyanate. Stannylene <b>1</b> reacts with ArNCS, giving a mixture of complex products, while <b>1</b> does not react with CO<sub>2</sub>.