The six-membered heavy atom heterocycles [Re-2(CO)(8)(mu-SbPh2)(mu-H)](2), 5, and Pd[Re-2(CO)(8)(mu-SbPh2)(mu-H)](2), 7, have been prepared by the palladium-catalyzed ring-opening cyclo-dimerization of the three-membered heterocycle Re-2(CO)(8)(mu-SbPh2)(mu-H), 3. The palladium atom that lies in the center of the heterocycle 7 was removed to yield S. The palladium removal was found to be partially reversible leading to an unusual example of host-guest behavior. A related dipalladium complex Pd2Re4(CO)(16)-(mu(4)-SbPh)(mu(3)-SbPh2)(mu-Ph)(mu-H)(2), 6, was also formed in these reactions of palladium with 3.