Syntheses and structures of lithiated sulfones Li[CR(R′)SO 2Ph] – C versus O bound lithium. [{Li{CH(Me)SO 2Ph}(thf)} ∞] – The structure of a C-bound derivative

Abstract

Sulfones RCH(R′)SO 2Ph were reacted with n-BuLi in thf/ n-hexane (R/R′ = H/Me, Me/Et, H/CH 2Ph) and toluene/ n-hexane (R/R′ = Me/Ph) yielding under deprotonation Li[CR(R′)SO 2Ph] which reacted with Me 3SiCl and n-Bu 3SnCl forming the requisite trimethylsilyl and tri( n-butyl)tin substituted derivatives R 3 ″ E - C ( R ) R ′ SO 2 Ph ( R 3 ″ E = Me 3 Si , n - Bu 3 Sn ) . Performing the reactions of RCH(R′)SO 2Ph with n-BuLi in n-hexane (instead of thf/ n-hexane) and toluene/ n-hexane, respectively, resulted in the precipitation of the organo lithium compounds Li[CR(R′)SO 2Ph] ( 1– 4) which were isolated as strongly moisture-sensitive yellow powders in essentially quantitative yields. Their identities were confirmed by 1H and 13C NMR spectroscopic measurements in thf- d 8. Solutions of each 1, 3, and 4 in thf/ n-hexane and thf/ n-pentane afforded crystals of each [{Li{CH(Me)SO 2Ph}(thf)} ∞] ( 1a), [{Li{CH(CH 2Ph)SO 2Ph}(thf)} ∞] ( 3a), and [{Li{CMe(Ph)SO 2Ph}(thf) 2} 2] ( 4a), respectively, whose structures were determined by single-crystal X-ray crystallography. The compounds 1a and 3a crystallize in 1D polymeric ladder-like structures. The strands of 1a are built-up by eight-membered Li 2C 2S 2O 2 rings having direct Li–C bonding interactions (Li–C 2.215(5) Å). The donor set of Li is completed by three oxygen atoms, one from the thf ligand and two from SO 2 groups of neighboring Li{CH(Me)SO 2Ph}(thf) entities. The strands of 3a are built-up of alternating Li 2S 2O 4 eight- and Li 2O 2 four-membered rings. Each lithium atom is coordinated to three oxygen atoms, two from O 2S(Ph)CHCH 2Ph groups and one from thf oxygen atom. There is no Li–C bonding. Compound 4a crystallizes in dimers consisting of eight-membered Li 2S 2O 4 rings in which the two lithium atoms are bridged by two O 2S(Ph)CHMePh groups. The coordination sphere of lithium is completed by two oxygen atoms of the thf ligands.