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)

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 P1̄, 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.