Structural aspects of lithium arenethiolate complexes with intramolecular coordinating amine donors

Abstract

Reaction of aryllithium reagents LiR (R = C6H4((R)-CH(Me)NMe2)-2 (1a), C6H3(CH2NMe2)2-2,6 (1b), C6H4(CH2N(Me)CH2CH2OMe)-2 (1c)) with 1 equiv of sulfur (1/8 S8) results in the quantitative formation of the corresponding lithium arenethiolates [Li{SC6H4((R)-CH(Me)NMe2)-2}]6 (3), [Li{SC6H3(CH2NMe2)2-2,6}]6 (4), and [Li{SC6H4(CH2N(Me)CH2CH2OMe)-2}]2 (5). Alternatively, 3 can be prepared by reacting the corresponding arenethiol HSC6H4((R)-CH(Me)NMe2)-2 (2) with nBuLi. X-ray crystal structures of lithium arenethiolates 3 and 4, reported in abbreviated form, show them to have hexanuclear prismatic and hexanuclear planar structures, respectively, that are unprecedented in lithium thiolate chemistry. The lithium arenethiolate [Li{SC6H4(CH2N(Me)CH2CH2OMe)-2}]2 (5) is dimeric in the solid state and in solution, and crystals of 5 are monoclinic, space group P21/c, with a = 17.7963(9) Å, b = 8.1281(7) Å, c = 17.1340(10) Å, = 108.288(5), Z = 4, and final R = 0.047 for 4051 reflections with F > 4(F). Hexameric 4 reacts with 1 equiv of lithium iodide and 2 equiv of tetrahydrofuran to form the dinuclear adduct [Li2(SAr)(I)(THF)2] (6). Crystals of 6 are monoclinic, space group P21/c, with a = 13.0346(10) Å, b = 11.523(3) Å, c = 16.127(3) Å, = 94.682(10), Z = 4, and final R = 0.059 for 3190 reflections with F > 4(F).