Heavier alkaline‐earth catalyzed dehydrocoupling of silanes and alcohols for the synthesis of metallo‐polysilylethers

Michael Hill, Louis Morris, Mary Mahon, Ian Manners, George Whittell, Fred McMenamy

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Abstract

The dehydrocoupling of silanes and alcohols mediated by heavier alkaline‐earth catalysts is described. Primary, secondary, and tertiary alcohols can be coupled to phenylsilane or diphenylsilane, whilst tertiary silanes are less tolerant to bulky substrates. Some control over reaction selectivity towards mono‐, di‐, or tri‐substituted silylether products was achieved through alteration of stoichiometry, conditions and catalyst. The ferrocenyl silylether, FeCp(CpSiPh(OBn)2), was prepared and fully characterized using barium catalysis. Stoichiometric experiments suggested a reaction manifold involving the formation of Ae‐alkoxide and hydride species. Mechanistic experiments suggested a complex reaction mechanism involving dimeric or polynuclear active species, whose kinetics are highly dependent on variables such as the identity and concentration of the pre‐catalyst, silane, and alcohol. Ferrocene‐containing poly‐and oligosilylethers with ferrocene pendent to‐ or as a constituent of the main polymer chain were prepared from Fe(CpSiPhH2)2 with diols 1,4‐(HOCH2)2‐(C6H4) and 1,4‐(CH(CH3)OH)2(C6H4), respectively. The resultant materials were characterized by NMR spectroscopy, gel permeation chromatography (GPC) and DOSY NMR spectroscopy, with estimated molecular weights in excess of 20,000 Da. The iron centers display reversible redox behavior and thermal analysis showed them to be promising precursors to magnetic ceramic materials.
Original languageEnglish
JournalChemistry - A European Journal
Early online date3 Jan 2020
DOIs
Publication statusE-pub ahead of print - 3 Jan 2020

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