The complexes [C6H6O(CO2CH3)(2)R]PdI(PPh(3)) (R = p-anisyl (4), m-anisyl (5), p-tolyl (6), phenyl (7), 1-naphthyl (8) and 2-thienyl (9)) were prepared by treating Pd(PPh(3))(2)(R)I with exo-5,6-dicarbomethoxy-7-oxanorbornene (3) or from the reaction of Pd(PPh(3))(4) with the corresponding organic iodide (RI) followed by addition of 3 and methyliodide. In complexes 4-8, the carbon-carbon double bond between ipso and ortho positions of the aryl ring attached to the 7-oxanorbornyl group is weakly bound to the palladium (II) center in a eta 2 fashion, in addition to the three ligands-the 7-oxanorbornyl group, PPh, and I-. This eta(2)-interaction leads to a dramatic upfield shift of C-13 NMR signals of the ipso carbons by 30-40 ppm. Variable-temperature NMR studies indicate that complexes 4-7 are nonrigid on the NMR time scale. Rotation of the weakly eta(2)-bound aryl group is proposed to account for the observed fluxional behavior. In contrast to 4-7, 8 is static at room temperature, presumably, due to the unsymmetrical nature and the large size of the naphthyl group. In complex 9, the sulfur atom in the thienyl group is coordinated to the palladium center and no intramolecular eta(2)-bonding is involved.