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 η2-chelating formamidinate ligands in the solid state