A Flexible Approach to Strained Sandwich Compounds: Chiral [1]Ferrocenophanes with Boron, Gallium, Silicon, and Tin in Bridging Positions

作者：Sadeh Saeid; Schatte Gabriele; Mueller Jens

来源：Chemistry - A European Journal, 2013, 19(40): 13408-13417.

DOI：10.1002/chem.201301991

• boron
• ferrocenophanes
• gallium
• metallocenes
• silicon
• tin

The enantiomerically pure dibromoferrocene 3 [(S-p,S-p)-1,1-dibromo-2,2-di(isopropyl)ferrocene], equipped with two iPr groups in positions, was prepared using known Ugi amine chemistry. Species 3 was targeted in order to gain access to new [1]ferrocenophanes ([1]FCPs) to be used as monomers for ring-opening polymerization. The iPr groups on the sandwich unit were introduced to stabilize bridging moieties, as well as to increase solubilities of targeted metallopolymers. The planar chiral dibromide 3 can quantitatively be lithiated at 0 degrees C [2 equiv nBuLi, hexanes/thf (9:1), 30min]. Salt-metathesis reactions with respective element dichloride species gave chiral [1]FCPs with a variety of bridging moieties [ERx = Ga[2-(Me2NCH2)C6H4] (4a), SiMe2 (4b), SntBu(2) (4c), BNiPr2 (4d)]. The new [1]FCPs were fully characterized including single-crystal X-ray analysis. The stabilizing iPr groups on the Cp rings increase the thermal stabilities of 4b-d compared to known [1]FCPs, equipped with the same bridging moieties. All three compounds 4b-d are volatile and could be isolated by vacuum sublimation. Our new approach to [1]FCPs has the potential to overcome many of the existing difficulties in ferrocenophane chemistry, such as limited stability of starting monomers and low solubilities of resulting polyferrocenes.

• 出版日期2013-9-27