Synthesis and Reactivity of Amino(ylide)stannylenes

Abstract

The synthesis of two stable monoylide‐substituted stannylenes of type YCNSnR [R = Cl (1) or N(SiMe3)2 (2), and YCN = Ph3P(CN)C] starting from the cyanido‐substituted α‐metallated ylide YCN‐K and SnCl2 or (SiMe3)2NSnCl is reported. Coordination of the cyano group to the tin center results in the dimerization of both stannylenes 1 and 2 in the solid state as well as in solution, where syn‐ and anti‐isomers are present. X‐ray diffraction analyses in combination with DFT calculations revealed that the π‐electron density of the ylide ligand is predominantly shifted into the cyano moiety rather than towards the tin center. This results in a strong preference of the dimers over the monomers, which is further emphasized by the reaction with 2,5‐di‐tert‐butylhydroquinone, which undergoes a [1+4] addition to the tin center to yield a spiro compound while preserving the cyclic core of the dimer. In contrast, phenyl isocyanate and dicyclohexylcarbodiimide insert into the Sn‐Cylide bond, ultimately leading to the cleavage of the dimer and the formation of monomeric stannylenes with an ylide‐substituted thioamidato and amidinato ligand, respectively.