The reaction of lead acetate with (CO)(9)Co-3(mu(3)-CCOOH) leads to the formation of [Pb{(CO)(9)Co-3(mu(3)-CCO2)}(2)](n), I, in high yield. The structure of I exhibits unusual six-coordinate Pb(II) centers with two asymmetrical chelating cluster carboxylates (C22Co6PbO22; triclinic ; a = 8.119(1), b = 14.346(2), c = 14.660(2) Angstrom; alpha = 102.18(1), beta = 99.01(1), gamma = 97.30(1)degrees; Z = 2). One oxygen of each cluster carboxylate ligand bridges between adjacent lead atoms such that a chainlike extended structure is found in the solid state without the presence of solvent or water. I is converted stepwise on pyrolysis into two metastable forms of solid materials (designated LT and HT), each of which has been characterized spectroscopically. The hydrogenation of 2-butenal as a test reaction shows that the LT catalyst exhibits selectivities similar to previous LT materials derived from other cobalt cluster metal carboxylates and that the HT material is totally inactive. The observed release of the lead core metal under HT activation conditions totally inactivates the catalyst and demonstrates exposure of the core metal in the HT form of these novel catalysts.