Lewis-base adducts of main Group 1 metal compounds. Part 3. Synthesis and structural systematics of [LiXL3] and [L′2LiX2LiL′2] systems (X = Cl, Br, or I; L = 3,5-Me2C5H3N, L′= 2-MeC5H4N)

Abstract

Complexes [LiXL₃] and [L′₂LiX₂LiL′₂](X = Cl, Br, or I; L = 3,5-dimethylpyridine, L′= 2-methylpyridine) have been synthesized by recrystallization of the anhydrous lithium halide from the parent base and their stoicheiometries and structures confirmed and defined by single-crystal X-ray structure determination at 295 K; the structures are closely related to those of their copper(I) analogues. [LiClL₃] and [LiBrL₃] are rhombohedral, space group R3c, with a≈ 10.3 Å, α≈ 96°, Z= 2, the molecules being disposed on three-fold crystallographic axes. [LiIL₃] is monoclinic, space group Cc, with a= 13.260(6), b= 15.178(8), c= 11.625(5)Å, β= 97.49(3)°, Z= 4. The structures were refined to residuals of 0.044, 0.036, 0.033 for 406, 302, and 1 307 independent observed reflections respectively. Li–Cl, –Br, –I are 2.320(9), 2.51(2), and 2.80(1)Å respectively. [L′₂LiX₂LiL′₂] are all triclinic, space group P, with a≈ 9.5, b≈ 9.2, c≈ 8.9 Å, α≈ 107, β≈ 117, γ≈ 95°(chloride, bromide), α≈ 68, β≈ 85, γ≈ 75°(iodide), Z= 1 dimer. Residuals were 0.064, 0.041, 0.041 for 1 399, 1 846, 2 030 independent observed reflections respectively. 〈Li–X〉 are 2.38, 2.56, 2.80 Å(average) respectively.