Rhodium(I)-centered cyclotriveratrylene

Article abstract of DOI:10.1002/recl.19951140902

The rigid bowl-shaped molecule cyclotriveratrylene (CTV,1) was provided with short and long spacer arms terminating in triphenyl phosphite functions.These CTV ligands were used to immobilize a rhodium(I)-carbonyl-hydride complex.The ligand with short spacers gave a rigid, strained complex with a trigonal-coordination sphere around the rhodium.The ligand with long flexible spacers allowed the formation of a large cavity after the complexation to the rhodium center.This cavity, however, is filled up by the spacer arms, as was indicated by NMR studies.Variable-temperature NMR experiments suggested that the H-Rh-CO dipole in the rhodium-CTV complex can adopt two orientations: one with the hydride group pointing away from the CTV cavity (low-temperature conformation) and one in which this orientation is inverted (high-temperature conformation).