Syntheses and structural studies of lithium complexes of 2-amino-6-methylpyridine t

Lithiation of 2-amino-6-methylpyridine (C5H3NMeNH2) occurred smoothly in diethyl ether (OEt2) or hexaneAWAJV'-tetramethylethylenediamine (tmeda) affording [Li(C5H3NMeNH)(OEt2)0.5] 1 or [Li(C5H3NMeNH)-(tmeda)] 2. These complexes are extremely moisture sensitive and rapidly yield [Li8(CjH3NMeNH)6(O)(OEt2)2] 3 and [Li8(C5H3NMeNH)6(O)(tmeda)2] 4 respectively, upon exposure to limited amounts of water. On treatment of 1 with dimethylsilicone, insertion of dimethylsilicone into the Li-N bond occurs affording [Li4(C5H3NMeNHSi-Me2O)4] 5. All complexes were characterised by spectroscopic and X-ray crystallographic methods. Complexes 3 and 4 reveal octanuclear centrosymmetric structures with an octahedral oxygen centre bound by six lithium atoms, and in 4 a monodentate tmeda ligand is identified. Compound 5 is tetranuclear with an Li4O4 pseudo-cubane core with each of these lithium atoms involved in six-membered chelate rings comprised of N-C-N-Si-O atoms with the lithium bound to the terminal N and O heteroatoms.