Effect of Adamantyl Groups Along the Upper Rim of the Macrocycle Backbone on the Crystal Structure of Mixed-Valence \(\text{\{Mn}_{\text{2}}^{\text{II}}\text{Mn}_{\text{2}}^{\text{III}}\text{\}}\) Manganese Complexes Based on Calix[4]Arene and 2,2'-Bipyrimidine

Abstract

Two new tetranuclear \(\{\text{Mn}_{2}^{\text{II}}\text{Mn}_{2}^{\text{III}}\}\) clusters are obtained and studied by single crystal X-ray diffraction. They have similar coordination motifs involving p-H-calix[4]arene HCA or p-adamantylcalix[4]arene AdCA and 2,2′-bipyrimidine as N,N-donor chelating coligand. Two factors affecting the controlled cluster core deformation are revealed: the involvement of 2,2′-bipyrimidine in coordination with Mn(II) ions decreases the Mn^II–Mn^II distance; the introduction of bulky p-adamantyl groups along the calix[4]arene upper rim increases the Mn^III–Mn^III distance. Moreover, the presence of bulky substituents at the macrocycle platform is shown to change the molecular arrangement in the crystal, which leads to the formation of a porous crystal structure.