Synthesis and characterization of trimethylsilylmethyl-, bis(trimethylsilyl)methyl-and silyl-substituted cyclopentadienes and their alkali metal complexes

Abstract

A series of new Me 3SiCH 2–, (Me 3Si) 2CH–, Me 2Bu tSi– or Me 3Si– substituted cyclopentadienes and some of their alkali metal complexes has been prepared. Alkylation or silylation of NaC 5H 5 with (Me 3Si) 2CHBr or Bu tMe 2SiCl in tetrahydrofuran yielded C 5H 5{CH(SiMe 3) 2} 1 (Cp RH) or C 5H 5(SiMe 2Bu t) 2 (Cp tH) and C 5H 4(SiMe 2Bu t) 2 3 (Cp ttH), respectively. Metallation of 1, 2 or 3 with LiBu n, NaNH 2 or KH gave MCp R (M=Li 4, Na 5 or K 6), NaCp t 7 or MCp tt (M=Li 8 or K 9). Treatment of 6 with (Me 3Si) 2CHBr produced C 5H 4[CH(SiMe 3) 2] 2 10 (Cp RRH). Addition of Me 2NCH 2CH 2NMe 2 (TMEDA) to 4 or 8 afforded [LiCp R(TMEDA)] 11 or [LiCp tt(TMEDA)] 12. From 6 and Me 2SiCl 2 Me 2Si[C 5H 4CH(SiMe 3) 2] 2 13 [Me 2Si(Cp RH) 2] was obtained and converted into its potassium salt Me 2Si(Cp RK) 2 14. Metallation of C 5H 3(SiMe 3) 3 (Cp‴H) with LiBu n, NaNH 2 or KH in tetrahydrofuran yielded [LiCp‴(THF) 3] 15, NaCp‴ 16 or KCp‴ 17, respectively. Addition of MeN(CH 2CH 2NMe 2) 2 (PMDETA) to 16 afforded [NaCp‴(PMDETA)] 18. Treatment of 6 with Me 3SiCl gave C 5H 4(SiMe 3){CH(SiMe 3) 2} (Cp′ RH) 19 which, with KH, underwent a dyotropic transformation in yielding [KC 5H 2(SiMe 3) 2-2,4-CH 2SiMe 3-1] 20. Each of the new compounds 1–20 was characterized by multinuclear NMR spectroscopy ( 1H, 13C, 29Si or 7Li) and C, H, N elemental analysis (not 1), and in the case of the neutral cyclopentadienes, by GC/MS. The molecular structure of the crystalline complex 18 was also established by X-ray crystallography, as was that of [Li C 5H 3Bu 2 t-1,3)(TMEDA)] 21.