Directed Positioning of Organometallic Fragments Inside a Calix[4]arene Cavity

Abstract

A hemispherical diphosphane based on a calixarene allows encapsulation of reactive M-R fragments (M=transition metal; R=H, alkyl, CO) inside the calixarene cavity. The ruthenium complex 1 has an unprecedented sandwich structure that contains a CO ligand confined between two phosphane-substituted phenyl rings. The separation between the CO segment and the two aromatic rings is only 2.75 Å!