ELECTROPHILIC ADDITION TO AN IRIDATHIACYCLOPENTENE COMPLEX - SYNTHESIS OF THE 1ST METALLATHIOPHENE

The reactivity of the unsaturated five-membered iridathiacycle CH2=C-CH=CH-S-Ir(PEt3)33(H) (1) toward simple electrophiles has been investigated. Protonation occurs at the basic exocyclic methylene carbon, generating [CH3-C-CH-CH-S-Ir(PEt3)3. (H)]+X- (2a, X- = BF4-; 2b, X- = O3SCF3-), the first example of a ''metallathiophene''. In contrast, methylation of 1 occurs at the nucleophilic sulfur center, producing [CH2=C-CH-S(CH3)-Ir(PEt3)3-(H)]+X-(3a,X-=BF4-;3b,X-=O3SCF3-). S-ray crystal structures of 2a and 3b have been obtained.