Isolation and Structures of Polyarene Palladium Nanoclusters.

We report that surrounding coordination of neutral six-membered arene rings affords molecularly well-defined organotransition metal nanoclusters. With the use of [2.2]paracyclophane as the face-capping arene ligand, we have isolated two polyarene palladium nanoclusters, one consisting of a hexakis-arene ligand shell and a hexagonal close-packed Pd 13 anticuboctahedron trichloride core, and the other consisting of an octakis-arene ligand shell and a non-close-packed Pd 17 square gyrobicupola dichloride core, both with Pd-Pd direct bonding. The μ 4 -facial coordination mode of arene was discovered through the structural characterization of the Pd 13 cluster. Their Pd 13 and Pd 17 cores, which are distinct from the previously identified face-centered-cubic Pd 13 core surrounded by seven-membered cycloheptatrienyl, are explained by stereochemical and theoretical analyses.