Silicon-Bridged Bi- and Tridentate Lewis Acidic Host Systems

Connecting multiple organic spacer functions via silicon core units leads to various organosilanes that are excellently suited as backbones for poly-Lewis acids (PLAs). Using ethynyl spacer groups, rigid bis- and tris-dioxabenzoborole (BCat)-substituted PLAs were prepared. The fixed orientation of the Lewis acidic functions of the PLAs is reflected in their solid-state structures. Further flexible PLAs were obtained by hydroboration of vinylsilanes using 9-borabicyclo[3.3.1]nonane (9-BBN), which shows the flexibility of the backbone motif. Host-guest experiments of the bidentate representatives with pyridine demonstrate the ability of both PLA-types (BCat or 9-BBN) for complexing neutral guest molecules. The rigid host system shows additionally a 1 : 1 adduct formation using a bridged diamine as guest compound.

Automated summary

Connecting various organic spacer functions via silicon core units leads to organosilanes suitable as backbones for poly-Lewis acids, resulting in rigid and flexible PLAs. Solid-state structures and host-guest experiments demonstrate the characteristics of these PLAs, showing their ability to complex with neutral guest molecules.