Lewis-Base Adducts of Main Group 1 Metal Compounds. X. Lithium Bromide and Iodide Complexes With Acetonitrile (1 : 2, 1 : 4 Respectively)

Abstract

Although only sparingly soluble in acetonitrile, lithium(1) bromide and iodide crystallize as acetonitrile adducts, structurally characterized as LiX/MeCN 1 : 2 and 1 : 4 respectively by single-crystal structure determinations. The bromide is a µ,µ′-dibromo-bridged dimer , ( MeCN )₂LiBr₂Li( NCMe )₂)] (monoclinic, P2₁/n, a 7.624(2), b 12.61 2(2), c 8.047(3) Å , β 98.94(3)°p; Z 2 dimers; R 0.038 for No 1081 'observed' reflections); Li-Br, N 2.534(7), 2.492(8); 2.031(9), 2.047(8) Å respectively, with Li…Li, 3.17(1); Br…Br, 3.8989(9) Å respectively. The iodide is ionic, [Li( NCMe )₄]⁺1^- (orthorhombic, P2₁22_1, a 20.66(1), b 12.208(6), c 8.4296) Å, Z 6; R 0.062 for N_o 866).