Unlocking the Metalation Applications of TMP-powered Fe and Co(II) bis(amides): Synthesis, Structure and Mechanistic Insights.

Typified by LiTMP and TMPMgCl.LiCl, (TMP=2,2,6,6-tetramethylpiperidide), s-block metal amides have found widespread applications in arene deprotonative metalation. On the contrary, transition metal amides lack sufficient basicity to activate these substrates.

Lateral Metallation and Redistribution Reactions of Sodium Ferrates Containing Bulky 2,6-Diisopropyl-N-(trimethylsilyl)anilide Ligands.

Alkali-metal ferrates containing amide groups have emerged as regioselective bases capable of promoting Fe-H exchanges of aromatic substrates. Advancing this area of heterobimetallic chemistry, a new series of sodium ferrates is introduced incorporating the bulky arylsilyl amido ligand N(SiMe )(Dipp) (Dipp=2,6-iPr -C H ). Influenced by the large steric demands imposed by this amide, transamination of [NaFe(HMDS) ] (HMDS=N(SiMe ) ) with an excess of HN(SiMe )(Dipp) led to the isolation of heteroleptic [Na(HMDS) Fe{N(SiMe )Dipp}] (1) resulting from the exchange of just one HMDS group.

Facilitating the Ferration of Aromatic Substrates through Intramolecular Sodium Mediation.

Exploiting cooperative effects between Na and Fe 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 amide Fe(HMDS) 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.

Lithium-mediated Ferration of Fluoroarenes.

While fluoroaryl fragments are ubiquitous in many pharmaceuticals, the deprotonation of fluoroarenes using organolithium bases constitutes an important challenge in polar organometallic chemistry. This has been widely attributed to the low stability of the generated aryl lithium intermediates that even at -78 °C can undergo unwanted side reactions. Herein, pairing lithium amide LiHMDS (HMDS = N{SiMe₃}₂) with Fe(HMDS)₂ enables the selective deprotonation at room temperature of pentafluorobenzene and 1,3,5-trifluorobenzene the mixed-metal base [(dioxane)LiFe(HMDS)₃] (1) (dioxane = 1,4-dioxane).

Boosting Conjugate Addition to Nitroolefins Using Lithium Tetraorganozincates: Synthetic Strategies and Structural Insights.

We report the first transition metal catalyst- and ligand-free conjugate addition of lithium tetraorganozincates (R ZnLi ) to nitroolefins. Displaying enhanced nucleophilicity combined with unique chemoselectivity and functional group tolerance, homoleptic aliphatic and aromatic R ZnLi provide access to valuable nitroalkanes in up to 98 % yield under mild conditions (0 °C) and short reaction time (30 min). This is particularly remarkable when employing β-nitroacrylates and β-nitroenones, where despite the presence of other electrophilic groups, selective 1,4 addition to the C=C is preferred.

Utilising Sodium-Mediated Ferration for Regioselective Functionalisation of Fluoroarenes via C-H and C-F Bond Activations.

Pairing iron bis(amide) Fe(HMDS) with Na(HMDS) to form new sodium ferrate base [(dioxane) ⋅NaFe(HMDS) ] (1) enables regioselective mono and di-ferration (via direct Fe-H exchange) of a wide range of fluoroaromatic substrates under mild reaction conditions. Trapping of several ferrated intermediates has provided key insight into how synchronised Na/Fe cooperation operates in these transformations. Furthermore, using excess 1 at 80 °C switches on a remarkable cascade process inducing the collective twofold C-H/threefold C-F bond activations, where each C-H bond is transformed to a C-Fe bond whereas each C-F bond is transformed into a C-N bond.

Synthetic, structural and magnetic implications of introducing 2,2'-dipyridylamide to sodium-ferrate complexes.

Using a transamination approach to access novel Fe(ii) complexes, this study presents the synthesis, X-ray crystallographic and magnetic characterisation of a series of new iron complexes containing the multifunctional 2,2-dipyridylamide (DPA) ligand using iron bis(amide) [{Fe(HMDS)}] and sodium ferrate [{NaFe(HMDS)}] (1) as precursors (HMDS = 1,1,1,3,3,3-hexamethyldisilazide). Reactions of DPA(H) with 1 show exceptionally good stoichiometric control, allowing access to heteroleptic [(THF)·NaFe(DPA)(HMDS)] (3) and homoleptic [{THF·NaFe(DPA)}] (4) by using 1 and 3 equivalents of DPA(H), respectively. Linking this methodology and co-complexation, which is a more widely used approach to prepare heterobimetallic complexes, 3 can also be prepared by combining NaHMDS with heteroleptic [{Fe(DPA)(HMDS)}] (2).