Cage-like manganesesilsesquioxanes: features of their synthesis, unique structure, and catalytic activity in oxidative amidations

An extended series of Mn-based cage-like phenylsilsesquioxanes were obtained via convenient self-assembly reactions and complexations with 1,10-phenanthroline. The structural features of these cage complexes such as (i) various nuclearities and types of silsesquioxane ligands, (ii) encapsulations of hydroxide and chloride species, and (iii) spontaneous oxidations of Mn-II to Mn-III are established by single-crystal X-ray diffraction, including the use of synchrotron radiation. One of the synthesized compounds represents a unique feature among metallacomplexes - the presence of three metal ions with different oxidation states (Na-I, Mn-II, and Mn-III). Furthermore, the first-ever evaluation of Mn-silsesquioxanes as precatalysts in oxidative amidation (OA) reactions allowed us to develop a very effective protocol of OA of alcohols and aldehydes with low loading of Mn (5 mol% and 2.5 mol%, respectively).