Novel phosphanylcalix [6]arenes having mono-O-diphenylphosphanylmethyl (3) and mono-O-(4-diphenylphosphanylphenyl)methyl substituents (5) have been synthesized. The structures of these monophosphanylcalix[6]arenes were determined by NMR spectroscopy, mass spectrometry, and Xray crystal structure analysis. The X-ray structure reveals that 3 adopts a flattened 1,2,3-alternate conformation in the crystalline state, while the NMR spectra show that 3 and 5 have a cone conformation in solution. Structure optimization and energy calculations for 3 and 5 at the B3LYP/LANL2DZ-CONFLEX5/MMFF94s level of theory show that the cone

A novel capsule-shaped Ir(I) and Rh(I) cationic complexes with a triphosphinocalix[6]arene as a ligand were synthesized. These complexes showed dynamic behavior with size-selective molecular encapsulation, which was confirmed by variable-temperature 31P{1H} NMR measurement in the presence of various molecules.