Hexadentate Poly‐Lewis Acids Based on 1,3,5‐Trisilacyclohexane
Fabian Schäfer, Beate Neumann, Hans‐Georg Stammler, Norbert W. Mitzel
Abstract
Abstract 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, SiCl 3 , SiCl 2 Me or SiClMe 2 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 TfOSiMe 2 ‐C 2 H 4 ‐ 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).