Abstraction of thioethers

Because a-alkoxyalkyl iron complexes are thermally unstable [467] they cannot be stored for long periods of time. More suitable carbene precursors are the corresponding a-(dimethylsulfonium)alkyl complexes, which can be stored indefinitely under ambient conditions [468-473], These complexes are prepared by S-alkylation of a-(methylthio)alkyl complexes, which can be prepared by alkylation of metallates with a-halothioethers, by addition of C-nucleophiles to (alkylthio)carbene complexes, or by addition of thiols to carbene complexes. 

Alternatively, a-(dialkylsulfonium)alkyl iron complexes can be prepared from a-haloalkyl iron complexes by silver- or thallium-promoted nucleophilic substitution with thioethers [474], 

---