Carbosilane Metallodendrimers with Cyclopentadienyldichlorotitanium(IV) End Groups

Dendritic polyols of the second and third generation 2G-OH₈ (1), 2G-OH₁₆ (2), and 3G-OH₁₆ (3) were prepared by hydroboration/oxidation of allyl-terminated carbosilane dendrimers and used as supports for the immobilization of cyclopentadienyltrichlorotitanium(IV) complexes via alcoholysis. The reaction of 1–3 with CpTiCl₃ gave metallodendrimers 2G-(OTiCpCl₂)₈ (4a), 2G-(OTiCpCl₂)₁₆ (5a), and 3G-(OTiCpCl₂)₁₆ (6a), respectively, whereas the reaction of 1 and 3 with CpSi^FTiCl₃ (CpSi^F = C₅H₄SiMe₂CH₂CH₂C₈F₁₇) yielded peripherally fluorinated metallodendrimers 2G-(OTiCpSi^FCl₂)₈ (4b) and 3G-(OTiCpSi^FCl₂)₁₆ (6b). All metallodendrimers were characterized by multinuclear NMR spectroscopy. The suggested structures were supported by comparison with model 1-propoxycomplexes 10a,b. To identify side products of the alcoholysis reaction, hydrolytic behavior of the starting trichloro complexes was studied both in solid state and in solution. The main products of hydrolysis in solution were identified as μ-oxocomplexes 8a,b whereas hydrolysis in solid state yielded mainly hydroxycomplexes 7a,b.