Alternativ-Liganden. XXI. Neue Donor/Akzeptor-Liganden Me2PCH2CH2SiFnMe3-n,Me2PCH2CH2SiR(C6H4F)2 und (2-Me2PC6H4)SiXMe2

Alternative Ligands. XXI. Novel Donor/Acceptor Ligands Me₂PCH₂CH₂SiF_nMe_3-n, Me₂PCH₂CH₂SiR(C₆H₄F)₂, and (2-Me₂PC₆H₄)SiXMe₂ Donor/acceptor ligands of the type Me₂PCH₂CH₂SiX₃ X = Cl ( 1 ), F ( 2 ), Me ( 3 ), OMe ( 4 )], (Me₂PCH₂CH₂)₂SiX₂ X = Cl ( 6 ), F ( 7 )], Me₂PCH₂CH₂SiX(C₆H₄F)₂ X = F ( 5 ), Me ( 8 )], and Me₂PCH₂CH₂SiX_nMe_3-nn = 1; X = Cl ( 10 ), F ( 11 ); n = 2; X = F ( 9 )] are prepared in yields between 42 and 95% by photochemical addition of Me₂PH to the corresponding vinylsilane precursors. In case of the halogen containing representatives formation of solid polyadducts, due to Lewis acid/base interaction between P-donor and Si-acceptor function, reduces the yields. Ligands of the type (2-Me₂PC₆H₄)SiXMe₂ X = NMe₂ ( 12 ), Cl ( 13 ), F ( 14 )] are obtained by two different routes (Abb. 3), using 2-chlorobromobenzene as the starting material. New compounds have been characterized by analytical (C, H) and spectroscopic (NMR, MS) investigations. In order to elucidate the associative properties compounds 2 and 9 were used for the following experiments:

• – Study of the influence of dissolution on the proton and fluorine resonances of 2 and 9 ,
• – investigation of the adduct equilibrium (–H₂CF₃Si←PMe₂CH₂–)n + nBF₃ → nF₃B←PMe₂CH₂CH₂SiF₃],
• – cleavage of the polyadduct of 2 using NH₄]F and Me₄N]F, respectively, for the formation of hexacoordinate complex anions Me₂PCH₂CH₂SiF₅]^2?.

The results obtained confirm the assumption that oligo- and polymerisation are due to P→Si interaction.