Linear carbosiloxane dendrimers with the end group [(eta(2)-C CH)Co-2(CO)(6)]

The preparation of the first-generation dendrimers Si(OCH2CH2CH2SiMe2OCH2C= CH)(4) (5) as well as Si(OCH2CH2- CH2SiMe2C=CSiMe3)(4) (7) from Si(OCH2CH2C H2SiMe2Cl)(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 w ere reacted with four equivalents of Co-2(CO)(8) (8), dendrimers Si(OCH2[(e ta(3)-C=CH)Co-2(CO)(6)])(4) (9), Si(OCH2CH2CH2SiMe2OCH2[(eta(2)-C=CH)Co-2(C O)(6)])(4) (10) and Si(OCH2CH2CH2SiMe2[(eta(2)-C=CSiMe3)Co-2(CO)(6)])(4) (1 1) were formed. These dendritic molecules possess as end-grafted entities h exacarbonyldicobalt-tetrahedrane fragments on their surface. Dendrimers 5, 7 and 9-11 were fully characterized by elemental analysis, spectroscopic st udies (IR,H-1-, C-13{H-1}-NMR) as well as gel-permeation chromatography.