Lewis-base adducts of main group 1 metal compounds. IV synthesis and structure of the XLiL3 system (X = Cl, Br, I, L = 4-t-Butylpyridine, and X = I, L = Quinoline)

Complexes [XLiL₃], X = Cl, Br, I; L = 4-t-butylpyridine, (l)-(3) have been synthesized by recrystallization of the anhydrous lithium halide from the parent base, and characterized structurally by single-crystal X-ray structure determination. (1) and (2) are isomorphous (monoclinic, P21), a≈11.8, b≈12.1, c≈11.8 Å, β 120°, Z 2 (R 0.051, 0.040 for N0 1491, 1499 ‘observed’ reflections); (3) is orthorhombic, Pbca, a 22.119(10), b 21.108(10), c 12.845(10) Å, Z 8, R 0.067 for N0 967., (l)-(3) are all pseudo-trigonal and contain four-coordinate XLiN3 arrays [Li-X, 2.33(1); 2.53(1); 2.76(4) Å Li-N, 2.03(l)-2.ll(l); 2.04(l)-2.09(2); 2.03(4)-2.07(4) Å], Similar data are also recorded for X = I, L = quinoline (4) [monoclinic, P21/c, a 15-684(6), 6 7.693(4), c 26.758(12) Å, β 107.71(3)°, Z 4; R 0.072, N0 3096; Li-I, 2.78(2); Li-N, 2.08(2)-2.13(2) Å]. While a close parallel may be drawn between the similarity of the chemistry of lithium(I) and copper(I) in respect of (l)-(3), (4) is unusual being the first XML3 derivative for a quinoline-type ligand; it is a monoquinoline solvate.