Unexpected formation of a silicon-centered spirocyclic oligosiloxane bearing eight pendant ferrocene units

Abstract

An intriguing but rare silicon-centered spirocyclic compound, spiro[5.5]octaferrocenylpentasiloxane (4) featuring silicon fused six-membered ferrocenyl-functionalized siloxane rings, has been obtained during the thermally induced transformation of triferrocenylsilane Fc3Si–H (1) into triferrocenylsilanol Fc3Si–OH (2), when N,N-dimethylformamide (DMF) was used as a solvent in the presence of the metal carbonyl Mo(CO)6. The unexpected formation of the maximally ferrocenyl substituted silicon centered spirocyclic 4 involves the obtention, and subsequent condensation, of different ferrocenylsilanol intermediates. Spirocyclic silicate 4 has been characterized using a combination of MALDI-TOF mass spectrometry, elemental analysis, and single crystal X-ray diffraction analysis