A new synthetic method for tricyclic laddersiloxanes, ladder‐type silsesquioxanes with defined structures, is developed based on intramolecular cyclization of hydrosilyl‐functionalized cyclic siloxanes. This method enables the construction of unprecedented laddersiloxanes with various ring sizes. Herein, the preparation of tricyclic laddersiloxanes containing 6‐8‐6‐, 8‐8‐8‐, or 12‐8‐12‐membered‐ring systems is reported. These products can be considered as bat‐shape siloxanes, owing to their rigid inorganic siloxane body with flexible oligosiloxane “wings” as side rings. The synthesized compounds are potential building blocks for well‐defined nanomaterials, porous materials, and host molecules.

Front Cover: New bat siloxanes fly to the moon: Tricyclic laddersiloxanes with larger side rings are prepared for the first time from Janus rings. The obtained novel, 12‐8‐12‐membered ring laddersiloxane has a rigid silsesquioxane body with flexible oligosiloxane “wings”. Like a real bat, they can move wings freely to apply into host molecules or highfunctional materials. This work is found in article number 2000608 by Masafumi Unno and co‐workers.