Chemistry of 2,3-dihydro-2-metallaphenalenes. Part 1. Synthesis of CHRSiMe2CHR′C10H6(R = R′= H; R = R′= SiMe3; and R,R′= H,SiMe3) and formation of the compound [{Li(Me2NCH2CH2NMe2)}2{CHSiMe2C(SiMe3)C10H6}]via decomposition of [{Li(Me2NCH2CH2NMe2)}2{1,8-(CHSiMe3)2C10H6}]; crystal structures of two polymorphs of the silicon heterocycle dilithium complex

Abstract

The complexes [{Li(tmen)}₂{1,8-(CHSiMe₃)₂C₁₀H₆}](9)(tmen =NNN′N′-tetramethylethylenediamine) and [{Li(tmen)}{[graphic omitted]₁₀H₆}](13) have been prepared via metallation of species formed by in situ Grignard trapping reactions of 1,8-(ClCH₂)₂C₁₀H₆ with SiMe₃Cl and SiMe₂Cl₂ respectively; synthesis of the siline, meso-[graphic omitted]₁₀H₆ from (9) is also described. In hexane, (9) decomposes to [{Li(tmen)}₂{[graphic omitted]₁₀H₆}](10) to yield the compound [graphic omitted]₁₀H₆ on the addition of aqueous HCl, the same product as that obtained from a reaction of (13) with SiMe₃Cl. The nature of (10) has been established by X-ray structure determination of two polymorphs, α and β, which differ both in the mode of interaction of the Li(tmen)⁺ moieties with the carbanion [η⁶:η³(α), cf.η⁴:η³(β)] and the conformation of the heterocyclic ring.