While cobalt complexes have already shown their potential for CÀ H and CÀ F bond activation of fluoroarenes, their reactivity as metalating agents via CoÀ H exchange towards these substrates has not been explored. Herein, we report a Co(HMDS) 2 [HMDS = N(SiMe 3 ) 2 ] system which, when synergistically enhanced via sodium amide Na(HMDS) mediation, can render chemo-and regioselective cobaltation of a series of fluoroarenes to produce a new class of homoleptic square planar [Na 2 CoAr 4 ] complexes. Density functional theory calculations elucidate the key roles of the Na/Co counterparts in a stepwise sodiation/cobalt transmetalation process, leading to this novel CÀ H metalation. Depending on the reaction stoichiometry, this process can occur inter-or intramolecularly, furnishing transient [NaCo(HMDS) 2 Ar] intermediates which can undergo ligand rearrangement to afford [Na 2 CoAr 4 ] with concomitant formation of Co(HMDS) 2 and [NaCo-(HMDS) 3 ].

Recent advances in cooperative chemistry have shown the enormous potential of main group heterobimetallic complexes for the functionalisation of aromatic molecules. Going beyond main group metal chemistry, here we provide an overview on the synthesis, structure and reactivity of bimetallic complexes which combine an alkali-metal (AM= Li, Na) with a divalent earth-abundant transition metal (M= Mn, Fe, Co, Ni), containing the utility silyl amide HMDS (HMDS = N(SiMe3)2). Advancing the understanding on how cooperative effects operate in these bimetallic (ate) systems, selected examples of their applications in deprotonative metalation are also discussed with special emphasis on the constitution of the metalated intermediates.

Heterobimetallic base NaCo(HMDS)3 [HMDS = N(SiMe3)2] enables regioselective di-cobaltation of activated polyfluoroarenes under mild reaction conditions. For 1,3,5-C6H2X3 (X= Cl, F), NaCo(HMDS)3 in excess at 80oC impressively induces the collective...

While cobalt complexes have already shown their potential for C−H and C−F bond activation of fluoroarenes, their reactivity as metalating agents via Co−H exchange towards these substrates has not been explored. Herein, we report a Co(HMDS)2 [HMDS=N(SiMe3)2] system which, when synergistically enhanced via sodium amide Na(HMDS) mediation, can render chemo‐ and regioselective cobaltation of a series of fluoroarenes to produce a new class of homoleptic square planar [Na2CoAr4] complexes. Density functional theory calculations elucidate the key roles of the Na/Co counterparts in a stepwise sodiation/cobalt transmetalation process, leading to this novel C−H metalation. Depending on the reaction stoichiometry, this process can occur inter‐ or intramolecularly, furnishing transient [NaCo(HMDS)2Ar] intermediates which can undergo ligand rearrangement to afford [Na2CoAr4] with concomitant formation of Co(HMDS)2 and [NaCo(HMDS)3].

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