Supramolecular Aggregation of Pd6Cl12, a Cluster of Comparable Size to a Fullerene, with Aromatic Donors and with C60

Molecular solids comprised of octahedra, hexagonal plates, and truncated icosahedra result from the co-crystallization of Pd 6 Cl 12, benzene and its methylated derivatives, and C 60 . Solutions of bis(benzonitrile)palladium(II) dichloride in benzene deposit deep red crystals of solvate-free Pd 6 Cl 12, 1, while solutions of bis(benzonitrile)palladium(II) dichloride in the following solvents or solutions produce binary or ternary compounds as follows: from mesitylene, Pd 6 Cl 12 ·(CH 3 ) 3 C 6 H 3 ( 2 ); from mesitylene/benzene, Pd 6 Cl 12 ·(CH 3 ) 3 C 6 H 3 ·0.5C 6 H 6 ( 3 ); from durene/benzene, Pd 6 Cl 12 ·(CH 3 ) 4 C 6 H 2 ( 4 ); from benzene/hexamethylbenzene, Pd 6 Cl 12 ·1.5(CH 3 ) 6 C 6 ( 5 ); from benzene/biphenyl, Pd 6 Cl 12 ·(C 6 H 5 ) 2 ( 6 ); and from benzene/fullerene C 60, Pd 6 Cl 12 ·0.5C 60 ·1.5C 6 H 6 ( 7 ). The geometric structures of each of these seven compounds have been determined by X-ray crystallography, and the electronic structure of Pd 6 Cl 12 has been probed with SCF−Xα−SW calculations. In each crystalline compound the structure of the Pd 6 Cl 12 unit is virtually invariant. It consists of an octahedral array of six palladium atoms that are surrounded by twelve equivalent chlorine atoms in edge-bridging sites. The long face-to-face Pd···Pd separations (4.675 Å in 1 ) indicate that there is no direct Pd−Pd bonding in the cluster. In 1 these octahedra interact with one another through pairwise Pd···Cl contacts. In 2, 3, 4, and 6, layer-like structures are found in which each Pd 6 Cl 12 cluster makes face-to-face contact with an arene moiety on opposite PdCl 4 faces and each arene makes contact with two Pd 6 Cl 12 clusters. In these four compounds, the clusters also make contact with each other through pairwise Pd···Cl contacts that are like those found in 1 . The structure of Pd 6 Cl 12 ·1.5(CH 3 ) 6 C 6 ( 5 ) is unique in that three hexamethylbenzene molecules make face-to-face contact with orthogonal faces of the Pd 6 Cl 12 cluster and the cluster−cluster separations are larger than those in 1 − 4 and 6 . The structure of Pd 6 Cl 12 ·0.5C 60 ·1.5C 6 H 6 ( 7 ) consists of a complex array of molecular components with face-to-face contacts between the benzene molecules and both C 60 and Pd 6 Cl 12 . Pd 6 Cl 12 itself dissolves in aromatic solvents. The electronic spectra of the resulting solutions show variations that are indicative of a degree of charge transfer between the Pd 6 Cl 12 cluster as an electron acceptor and the arene as an electron donor.