Lipophilic lithium alkoxides or dialkylboroxides; X-ray structures of [Li(µ-OR′)]2 and Li(OBR2)(tmeda), [tmeda =(Me2NCH2)2, R = CH(SiMe3)2, R′= CBut3 or BR2]

Abstract

Treatment of Bu^t₃COH or BR₂OH [R = CH(SiMe₃)₂] with LiBuⁿ yields the colourless crystalline [Li(µ-OR′)]₂, [R′= CBu^t₃(1) or BR₂(2)]; the dialkylboroxide (2) reacts with tmeda [tmeda =(Me₂NCH₂)₂], MeCOCI, or [Ti(η-C₅H₅)₂Cl₂] to yield Li(OBR₂)(tmeda)(3), BR₂OH, or [Ti(η-C₅H₅)₂(Cl)(OBR₂)], respectively; X-ray data on complexes (1)–(3) are compared with those for related LiO compounds, the two-co-ordinate lithium environment in (1) and (2), and the exceedingly short Li–O [1.677(5)Å] and O–B [1.308(8)Å] distances in (3) being noteworthy.