Special Siloxamides: Metal Movements in a Crystalline Molecular Box

Metal salts of [R−O−SiMe 2 −N−SiMe 2 −O−R] − and [R−N−SiR′ 2 − O−SiR′ 2 −N−R] 2− (R = t Bu, Me 3 Si, t BuMe 2 Si, Ph; R′ = Me, Et/Me, i Pr; Metal = Li, Na, K, Cu, Ag) have been synthesised and analysed in the crystalline state with respect to metal movements. Almost all compounds crystallize as dimers, for example Li 2 [ t BuO−SiMe 2 −N−SiMe 2 −O t Bu] 2 or Li 4 [ t BuN− SiMe 2 −O−SiMe 2 −N t Bu] 2 , and form different solid‐state phases. Whereas the Li atoms in the first example rotate at ambient temperature perpendicular to the NN axis of the molecule, they oscillate in the second example. The movements of the lithium atoms are coupled to ligand vibrations, and can be switched on and off by temperature changes. This switching is directly linked to phase transitions, that can be first order or second order. The other metallic atoms show no important dynamics, although phase transitions have also been found for these compounds.