Exploiting cooperative effects between Na and Fe II centres present in tris(amide) ferrate complexes has led to the chemoselective ferration of pentafluorobenzene, benzene, toluene, anisole, and pyridine being realised at room temperature. The importance of this bimetallic partnership is demonstrated by neither the relevant sodium amide (NaHMDS or NaTMP) nor the Fe II amide Fe(HMDS) 2 efficiently metallating these substrates under the conditions of this study. By combining NMR studies with the isolation of key intermediates and DFT calculations, we offer a possible mechanism for how these reactions take place, uncovering a surprising reaction pathway in which the metals cooperate in a synchronised manner. Although the isolated products are formally the result of Fe-H exchange, theoretical calculations indicate that the aromatic substrates undergo Na-H exchange followed by fast intramolecular transmetallation to Fe, thus stabilizing the newly generated aryl fragment.Heterobimetallic amide bases containing a complementary combination of an alkali metal with a less electropositive metal, such as Mg or Zn, have emerged as a powerful class of reagents for selectively deprotonating functionalised arenes. [1] Profiting from the cooperation between the two metals, these bimetallic strategies can offer greater functional group tolerance and special regioselectivities that conventional single-metal bases cannot match. [2] Through the isolation

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 ].

Exploiting cooperative effects between Na and FeII centres present in tris(amide) ferrate complexes has led to the chemoselective ferration of pentafluorobenzene, benzene, toluene, anisole, and pyridine being realised at room temperature. The importance of this bimetallic partnership is demonstrated by neither the relevant sodium amide (NaHMDS or NaTMP) nor the FeII amide Fe(HMDS)2 efficiently metallating these substrates under the conditions of this study. By combining NMR studies with the isolation of key intermediates and DFT calculations, we offer a possible mechanism for how these reactions take place, uncovering a surprising reaction pathway in which the metals cooperate in a synchronised manner. Although the isolated products are formally the result of Fe‐H exchange, theoretical calculations indicate that the aromatic substrates undergo Na‐H exchange followed by fast intramolecular transmetallation to Fe, thus stabilizing the newly generated aryl fragment.