Crystal engineering with molecular rods: binuclear complexes of bridging, nitrogen-donor ligands capped by organopalladium fragments

Abstract

Rod-shaped, binuclear complexes 2, 3 and 4 were prepared by coordinating the organopalladium fragment [Pd(RC 6H 2(CH 2SPh) 2)] + to the termini of the linear, bridging bidentate ligands 4,4′-bipyridine, 1,4-dicyanobenzene, and 1,2-bis(4,4′-dipyridinium)ethane. The X-ray structures of 2 (R = H), 3 (R = H), and 4 (R = p-MeO) were determined. Each complex is a “rod-shaped” cation with overall lengths of 20.6, 21.5, and 31.5 Å, respectively. In the crystals of complex 2, rod-shaped cations are aggregated by π-stacking interactions between the electron-rich palladated aromatic ring and the electron-poor bipyridyl rings in a perpendicular arrangement. In crystals of complex 3, rod-shaped cations are aggregated by π-stacking interactions between the electron-rich palladated aromatic ring and the electron-poor dicyano-substituted aromatic rings in a parallel arrangement. No intermolecular interactions were observed for the crystals of 4.