Lewis-base adducts of main Group 1 metal compounds. Part 2. Syntheses and structures of [Li₄Cl₄(pmdien)₃] and [LiI(pmdien)]

Crystallization of lithium chloride from its solution in excess NNN′N′N″-pentamethyldiethylene-triamine (pmdien) in hydrocarbon yilds a 4:3 adduct, characterised crystallographically as [Li₄Cl₄(pmdien)₃], crystals of which are monoclinic, space group P2₁/n, with a = 9.318(7), b = 34.91(2), c = 13.578(7) Å, β = 97.08(5)°, Z = 4 oligomers; R = 0.077 for 2 286 observed reflections. Lithium iodide yields a 1:1 mononuclear species, [LiI(pmdien)], crystals of which are orthorhombic, space group Pbam, with a = 14.895(8), b = 14.815(8), c = 13.550(8) Å, Z = 8; R = 0.063 for 913 observed reflections. In the iodide, there are two independent molecules, each with m symmetry and four-co-ordinate lithium [Li-I 2.75(3), 2.67(3) Å], whereas the chloride contains both four- and five-co-ordinate lithium atoms.