Facile dichloromethane activation and phosphine methylation. Isolation of unprecedented zwitterionic organozinc and organocobalt intermediates.

Both C-Cl bonds of CH(2)Cl(2) are readily activated by CoCl(2) and metallic Zn allowing quantitative methylation of phosphines; unprecedented zwitterionic Co(ii) and Zn(ii) intermediates have been characterized which display alpha-metallated phosphoniums.