Lineare Carbosiloxan-Dendrimere mit terminalen [(η2-CCH)Co2(CO)6]-Bausteinen

The preparation of the first-generation dendrimers Si(OCH2CH2CH2SiMe2OCH2CCH)4 (5) as well as Si(OCH2CH2CH2SiMe2CCSiMe3)4 (7) from Si(OCH2CH2CH2SiMe2Cl)4 (4) is described. While 5 can be synthesized by the reaction of 4 with HOCH2CCH (2) and NEt3 in 80% yield, 7 is accessible by treatment of 4 with LiCCSiMe3 (6) in 70% yield. When Si(OCH2CCH)4 (3), 5 and 7 were reacted with four equivalents of Co2(CO)8 (8), dendrimers Si(OCH2[(η2-CCH)Co2(CO)6])4 (9), Si(OCH2CH2CH2SiMe2OCH2[(η2-CCH)Co2(CO)6])4 (10) and Si(OCH2CH2CH2SiMe2[(η2-CCSiMe3)Co2(CO)6])4 (11) were formed. These dendritic molecules possess as end-grafted entities hexacarbonyldicobalt-tetrahedrane fragments on their surface. Dendrimers 5, 7 and 9–11 were fully characterized by elemental analysis, spectroscopic studies (IR, 1H-, 13C{1H}-NMR) as well as gel-permeation chromatography.