Synthesis of ansa-[n]silacyclopentadienyl-cycloheptatrienyl-chromium complexes (n = 1, 2): novel precursors for polymers bearing chromium in the backbone |
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Authors: | Bartole-Scott Alexandra Braunschweig Holger Kupfer Thomas Lutz Matthias Manners Ian Nguyen Thi-Loan Radacki Krzysztof Seeler Fabian |
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Institution: | Inorganic Rings and Macromolecules, Dept. of Chemistry, 80 St. George St., Toronto, Ontario M5S 3H6, Canada. |
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Abstract: | Reaction of (eta5-C5H4Li)(eta7-C7H6Li)Cr]tmeda with a variety of dialkyl(dichloro)silanes in aliphatic solvents afforded the corresponding 1]silatrochrocenophanes. Structural characterization by X-ray diffraction analysis of the 1]silatrochrocenophanes bearing Me2Si, (iPr)2Si, and silacyclobutane bridges revealed tilt angles alpha of 15.56(12) degrees , 15.8(1) degrees , and 16.33(17) degrees , respectively. Analogously, a 2]silatrochrocenophane (6) was prepared in excellent yield by reaction of (eta5-C5H4Li)(eta7-C7H6Li)Cr]tmeda with 1,2-dichloro-1,1,2,2-tetramethyldisilane. This complex also was characterized structurally and exhibited a tilt angle alpha of 2.60(15) degrees. The 1]silatrochrocenophane bearing the Me2Si bridge underwent facile and regioselective carbon-silicon bond cleavage with Pt(PEt3)4] to give a very high yield of an oxidative addition product. The ring-opening polymerization of these novel 1]silatrochrocenophanes afforded ring-opened chromium-based polymers. |
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Keywords: | ansa‐silametallocenes chromium metallocenes metallopolymers oxidative addition ring‐opening polymerization silicon |
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