Reactions of an Isolable Dialkylstannylene with Carbon Disulfide and Related Heterocumulenes

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 ArNCO [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 NC double bond of the isocyanate. Stannylene 1 reacts with ArNCS, giving a mixture of complex products, while 1 does not react with CO₂.