Mononuclear formamidinate complexes of lithium and sodium

Treatment of N, N -bis(aryl) formamidines (FXylH = N,N -bis(2,6-dimethylphenyl)formamidine, FEtH = N, N -bis(2,6-diethylphenyl) formamidine, FisoH = N,N -bis(2,6-diisopropylphenyl)formamidine) with nBuLi in the presence of tmeda (= N, N, N , N -tetramethylethylenediamine) led to deprotonation of the amidine affording [Li(FXyl)(tmeda)] (1), [Li(FEt)(tmeda)] (2) and [Li(Fiso)(tmeda)] (3) respectively. Similar treatment of FXylH and FisoH with [Na N(SiMe3)(2) in THF and pmdeta (= N, N, N , N , N -pentamethyldiethylenetriamine) yielded [Na(FXyl)(pmdeta)] (4) and [Na(Fiso)(pmdeta)] (5). All complexes were characterised by spectroscopy (NMR and IR) and X-ray crystallography. Due to the bulkiness of the formamidinate ligands and the multidentate nature of the supporting neutral amine ligands (tmeda and pmdeta), all compounds were mononuclear with eta(2)-chelating formamidinate ligands in the solid state.