A Dinuclear Metallobridged Super Aryl-Extended Calix[4]pyrrole Cavitand.

A super aryl-extended calix[4]pyrrole equipped with four oxazolo[4,5-b]pyrazinyl units at its upper rim is reported. Its Pt /Pd -metallobridged cavitand counterparts were obtained by treatment with 2 equiv of cis-protected metal corners, [M(dppp)(OTf) ] (dppp=1,3-(bis-diphenylphosphino)propane). The metal corners arranged their axial phenyl substituents near the aromatic walls of the cavitand leading to the formation of inclusion complexes as single conformers. We characterized the inclusion complexes in solution using NMR spectroscopy. Selected complexes were also characterized in the gas-phase and in the solid-state using mass spectrometry and X-ray diffraction analysis. The dimensions of the open portals of the dinuclear complexes were found to be dependent on the included guest. The results of DFT calculations served to explain the dissimilar complexation-induced shifts observed in the dinuclear inclusion complexes with mono- and bis-formamide guests.