Equilibrium formation of stable all-silicon versions of 1,3-cyclobutanediyl

Abstract

Main group analogues of cyclobutane-1,3-diyls are fascinating due to their unique reactivity and electronic properties. So far only heteronuclear examples have been isolated. Here we report the isolation and characterization of all-silicon 1,3-cyclobutanediyls as stable closed-shell singlet species from the reversible reactions of cyclotrisilenec-Si(3)Tip(4)(Tip=2,4,6-triisopropylphenyl) with the N-heterocyclic silylenesc-[(CR2CH2)(NtBu)(2)]Si: (R=H or methyl) with saturated backbones. At elevated temperatures, tetrasilacyclobutenes are obtained from these equilibrium mixtures. The corresponding reaction with the unsaturated N-heterocyclic silylenec-(CH)(2)(NtBu)(2)Si: proceeds directly to the corresponding tetrasilacyclobutene without detection of the assumed 1,3-cyclobutanediyl intermediate.