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(SiMe3)(Dipp) (Dipp=2,6‐iPr2‐C6H3). Influenced by the large steric demands imposed by this amide, transamination of [NaFe(HMDS)3] (HMDS=N(SiMe3)2) with an excess of HN(SiMe3)(Dipp) led to the isolation of heteroleptic [Na(HMDS)2Fe{N(SiMe3)Dipp}]∞ (1) resulting from the exchange of just one HMDS group. An alternative co‐complexation approach, combining the homometallic metal amides [NaN(SiMe3)Dipp] and [Fe{N(SiMe3)Dipp}2] induces lateral metallation of one Me arm from the SiMe3 group in the iron amide furnishing tetrameric [NaFe{N(SiCH2Me2)Dipp}{N(SiMe3)Dipp}]4 (2). Reactivity studies support that this deprotonation is driven by the steric incompatibility of the single metal amides rather than the basic capability of the sodium reagent. Displaying synergistic reactivity, heteroleptic sodium ferrate 1 can selectively promote ferration of pentafluorobenzene using one of its HMDS arms to give heterotrileptic [Na{N(SiMe3)Dipp}(HMDS)Fe(C6F5)]∞ (4). Attempts to deprotonate less activated pyridine led to the isolation of NaHMDS and heteroleptic Fe(II) amide [(py)Fe{N(SiMe3)Dipp}(HMDS)] (5), resulting from an alternative redistribution process which is favoured by the Lewis donor ability of this substrate. Influenced by the large steric demands imposed by the 2,6‐diisopropyl‐N‐(trimethylsilyl)anilide ligand, N(SiMe3)Dipp, new examples of chemical cooperativity on sodium ferrates have been disclosed. This includes: (a) the chemoselective ferration of pentafluorobenzene by a heteroleptic tris(amido) sodium ferrate; and, (b) the lateral metallation of a N(SiMe3)Dipp group at one Me of its SiMe3 substituent when attempting the co‐complexation of the sodium and iron (II) single‐metal amides.