We report the preparation of hexadentate poly-Lewis acids (PLA) based on 1,3,5-trisilacyclohexane backbones bearing two alkynyl groups attached to each of the silicon atoms. A rigid hexadentate PLA bearing six Lewis-acidic catecholatoboryl-substituents was prepared by a tin-boron exchange reaction. Its structure, determined by X-ray diffraction, is the first of a Lewis-acid-functionalised donor-free trisilacyclohexane. Flexible hexadentate PLA were prepared by hydroboration or hydrosilylation of hexavinyltrisilacyclohexane, resulting in PLA with six 9-BBN, SiCl3, SiCl2Me or SiClMe2 groups. The Lewis-acidity of the last one was increased by conversion with silver triflate, resulting in a PLA with six highly acidic silyl triflate groups attached to the 1,3,5-trisilacyclohexane unit as TfOSiMe2-C2H4- groups. Host-guest experiments of the above PLA demonstrated the suitability of the flexible representatives for complexation of neutral Lewis-based guest molecules under formation of 1 : 6 adducts (host: guest).
The document is publicly available on the WWW.