Synthesis and Reactivity of Bis(silylene)-Coordinated Calcium and Divalent Lanthanide Complexes

Divalent lanthanide complexes of Eu (1) and Yb (2) coordinated by a chelating pyridine‐based bis(silylene) ligand were isolated and fully characterized. Compared to the Eu$^{II}$ complex 1, the Yb$^{II}$ complex 2 presents a lower thermal stability, resulting in the activation of one Si$^{II}$−N bond and formation of an Yb$^{III}$ complex (3), which features a unique silylene‐pyridyl‐amido ligand. The different thermal stability of 1 and 2 points towards reduction‐induced cleavage of one Si$^{II}$−N bond of the bis(silylene) ligand. Successful isolation of the corresponding redox‐inert bis(silylene) Ca$^{II}$ complex (5) was achieved at low temperature and thermal decomposition into a Ca$^{II}$ complex (4) bearing the same silylene‐pyridyl‐amido ligand was identified. In this case, the thermolysis reaction proceeds through another, non‐redox induced, mechanism. An alternative higher yielding route to 4 was developed through an in situ generated silylene‐pyridyl‐amine proligand.