Interconversion of Highly Entangled Polyhedra into Concave Polyhedra by Nitrate-Induced Ternary Coordination

Abstract

Entangled (M3L2)n polyhedral complexes represent a unique class of supramolecular architectures that are stabilized by relatively weak metal–acetylene interactions in cooperation with conventional metal–pyridyl coordination. Counter-anion exchange of these complexes with a nitrate (NO3−) ion triggered formal metal insertion between the metal centers, and a heteroleptic ternary coordination mode with acetylenic, pyridyl, and nitrate donors was generated on the metal centers. As a result, the main frameworks of the polyhedral complexes M18L12 and M12L8 were formally extended into a new series of concave polyhedra having the compositions M21L12 and M13L8, respectively. This transformation also resulted in the local disconnection of the highly entangled trifurcate topology of the framework, providing clues toward the skeletal editing of extended and complex three-dimensional (3D) architectures.