Applying Na/Co(II) bimetallic partnerships to promote multiple Co-H exchanges in polyfluoroarenes.

Heterobimetallic base NaCo(HMDS) 3 [HMDS = N(SiMe 3 ) 2 ] enables regioselective di-cobaltation of activated polyfluoroarenes under mild reaction conditions. For 1,3,5-C 6 H 2 X 3 (X= Cl, F), NaCo(HMDS) 3 in excess at 80 °C impressively induces the collective cleavage of five bonds (two C-H and three C-X) of the substrates via a cascade activation process that cannot be replicated by LiCo(HMDS) 3 or KCo(HMDS) 3 .