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.