Syntheses and structures of Li, Fe, and Mo derivatives of N,N′-bis(2,6-diisopropylphenyl)-o-phenylenediamine

Abstract

Double deprotonation of N,N′-bis(2,6-diisopropylphenyl)-o-phenylenediamine (H₂L) with n-BuLi in THF yields the dilithium complex Li₂L(thf)₃. The reaction of Li₂L(thf)₃ with FeBr₂(thf)₂ and subsequent replacement of the solvent with toluene yield LFe(η⁶-toluene), which can also be synthesized from Fe(HMDS)₂(thf) and H₂L in toluene. The NMR data, bond lengths obtained from an X-ray diffraction study, and DFT calculations indicate that the diamide ligand L²⁻ undergoes oxidization to a radical ligand L¹⁻. Reaction of LFe(η⁶-toluene) with 1 atm CO yields the tricarbonyl complex LFe(CO)₃. MoCl₄(thf)₂ reacts with two equivalents of Li₂L(thf)₃ to yield (LiL)₂MoCl₂(thf)₄ in which the phenylene backbone of the ligand has been dearomatized. One-electron oxidation of Li₂L(thf)₃ by EuCl₃(dme)₂ yields the open-shell species LiL(OEt₂), which was characterized by X-ray crystallography and EPR spectroscopy.