Linear and Bent Cp*2Si: Reversible Phase Transition of a Key Molecule.

The solid‐state structure of decamethylsilicocene Cp*2Si with a bent and a linear molecule in the same unit cell was so far considered an exception in relation to the structures of its all‐bent heavier analogues Cp*2E with E=Ge, Sn, Pb. Here, we present the solution to this conundrum by reporting a low‐temperature phase, where all three symmetrically independent molecules are present in a bent formation. This reversible enantiotropic phase transition occurs in the temperature range between 80 K and 130 K and provides a rationale for the unexpected linear molecule based in entropy beyond hand‐waving explanations such as electronic reasons or packing effects. [ABSTRACT FROM AUTHOR]