Lewis-Base Adducts of Main Group 1 Metal Compounds. XV. Adducts of Lithium(I) Perchlorate With o-Methyl-Substituted Monodentate Pyridine Bases of Increasing Bulk

Abstract

Whereas recrystallization of Cu^IClO⁴ from the progressively bulky pyridine bases (L) pyridine ( py ), 2-methylpyridine (2-mpy) and 2,6-dimethylpyridine (2,6-dmpy) yields adducts of progressively diminishing base stoichiometry , n = 4, 3, 2 (in [CuL_n ](ClO₄)), recrystallization of LiClO₄ from the same bases yields adducts [Li( py )₄](ClO₄) and polymeric, perchlorate -bridged Li(2-mpy/2,6-dmpy)₂ ClO₄). The former is tetragonal, I4 a 12.479(5), c 7.009(8) Å , Z 2, and isomorphous with the copper analogue; R was 0.057 for 324 'observed' reflections, and Li-N 2.O66(7)Å [cf. Cu-N, 2.046(4) Å ]. Li(2-mpy)₂(ClO₄) is monoclinic, P2₁/c, a 16.004(4), b 10.020(3), c 8.831(5) Å, β 99.56(3), Z 4, R 0.047 for 1402 'observed' reflections, while Li(2,6-dmpy)₂(ClO₄) is monoclinic, C2/c, a 22.089(9), b 10.067(5), c 15.715(6) Å , β 110.54(3), Z 8, R 0.041 for 1991 'observed' reflections. The latter compounds have Li₂N₂O₂ coordination environments about the metal of an irregular nature, presumably in consequence of ligand hindrance.