2,2-Difluor-1,3-diaza-2-sila-cyclopentene - Synthesis and Reactions

N,N'-Di-tert-butyl-1,4-diaza-1,3-butadiene reacts with elemental lithium under reduction to give a dilitbium salt, which forms with fluorosilanes the diazasilacyclopentenes 1-4; (HCNCMe3)2SiFR, R = F (1), Me (2), Me3C (3), N(CMe3)SiMe3 (4). As by-product in the synthesis of 1, the tert-butyl-aminomethylene-tert-butyliminomethine substituted compound 5 was isolated, R = N(CMe3)+CH2-CH = NCMe3. 5 is formed in the reaction of 1 with the monolithium salt of the 1,4-diaza-1,3-butadiene in an enamine-imine-tautomerism. 1 reacts with lithium amides to give (HCNCMe3)(2)SiFNHR, 6-12, R = H (6), Me (7), Me2CH (8), Me3C (9), H5C6 (10), 2,6-Me2C6H3 (11), 2,6-(Me2CH)(2)C6H3 (12). The reaction of 12 with LiNH-2.6-(Me2CH)(2)C6H3 leads to the formation of (HCNCMe3)(2)Si(NHR)(2), (13). In the presence of n-BuLi, 12 forms a lithium salt which looses LiF in boiling toluene. Lithiated 12 adds this LiF and generates a spirocychc tetramer with a central eight-membered LiF-ring (14), [(HCNCMe3)(2)Si(FLiFLiNR)](4), R = 2,6-(Me2CH)(2)C6H3. ClSiMe3 reacts with lithiated 12 to yield the substitution product (HCNCMe3)(2)SiFN(SiMe3) R, (15). The crystal structures of 1, 5, 6, 9, 11, 13, 14 are reported.