Phosphine complexes of main group elements. A bis-phosphinomethyl lithiate as an anionic diphosphine ligand to lithium: synthesis and structure of {[Me2N(CH2)2NMe2]Li[(Me2P)C(SiMe3)2]2Li}

A novel type of Li complexation has been established by X-ray crystallography for the title compound revealing two distinctly different Li atoms, whereas the related compelxes {(thf)Li[(Me2P)2CX]}2(X = SiMe3, PMe2·, thf = tetrahydrofuran) feature equivalent environments for both lithium atoms.