Synthesis and characterization of substituted (thiomethyl)lithium compounds. Structures of [{Li(CH2SMe)(THF)}(infinity)] and [Li-2(CH2SPh)(2)(THF)(4)]

Bu3SnCH2SR reacts with BuLi in n-hexane(R = Me, Bu-t) and in n-hexane/THF (R = Ph) to give the solvate-free compounds LiCH2SR (R = Me (1a), Bu-t(1b), Ph (1c)). The constitution of 1 was determined by microanalysis and by NMR (H-1, C-13, Li-7) spectroscopy. 1b reacts with benzaldehyde and benzophenone to form PhCH(OH)(CH2SBu)-Bu-t (2) and Ph2C(OH)(CH2SBu)-Bu-t (3), respectively. Recrystallization of 1a and 1c from n-hexane/THF solutions gives [{Li(CH2SMe)(THF)}(infinity)] (1a') and [Li-2(CH2SPh)(2)(THF)(4)] (1c'), respectively. The structures of 1a' and 1c' were determined by single-crystal X-ray analysis. 1a' exhibits a polymeric ladder-like structure in which four-membered planar Li2C2 rings and six-membered Li2C2S2 rings are alternately arranged. 1c' crystallizes in the form of dimers with planar four-membered Li2C2 rings, but without sulfur coordination, at lithium.