| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2005: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
Phosphorus-bridged ferrocene oligomers possess a peculiar molecular structure which stems from a ferrocene moiety bearing a cylindrical shape. The oligomers can be further assembled via bonds with metal fragments, main group elements, and/or organic linkers. In this project, cyclic dimers are chosen as synthetic targets in order to elucidate their functionality as a ligand.
Preparation. P(NEt_2)-bridged [1.1]ferrocenophane, in which two P atoms are linked doubly with two 1,1'-ferrocenediy1 moieties, were prepared. Chlorination with HC1 of a mixture of syn-and anti-P(NEt_2)-bridged [1.1]ferrocenophane accompanied facile anti-to-syn conversion to give the syn isomer of PC1-bridged [1.1]ferrocenophane selectively, and treatment of the chlorophospine thus obtained with PhLi, Me_3SiCH_2Li, p-TolMgBr, or HNEt_2 afforded the corresponding diarylated, dialkylated, or diaminated compounds with the syn conformation retained.
Relative Stability. An and isomer of PPh-bridged [1.1]ferrocenophane could be converted almost completely to a syn isomer upon heating in toluene, indicative of the thermal instability of the and isomer over the syn isomer.
Utility. Sterically demanding and electron-donating diphosphine chelates described above are suitable for kinetically and/or thermodynamically stabilizing an unsaturated complex. Alkylation of a tetrahedral cobalt(II)dichloro complex bearing a Ph or Me_3SiCH_2 group on the phosphorus bridge gave a corresponding dialkyl-complex successfully, whereas similar alkylation of CoCl_2(dppp) resulted in a formation of Co^0(dppp)_2. The dialkyl complex obtained is the first coordinatively-unsaturated cobalt(II)(diphosphine)(dialkyl) complex isolated and characterized by X-ray analysis. This complex is expected to serve as a model intermediate in the cobalt(II)-catalyzed Heck-type reactions.
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