We also tested the effects of selectively adding boron or tin atoms to the clusters, and found that both additives strongly suppressed carbon deposition and also appeared to enhance stability with respect to thermal sintering. Neither boron nor tin was ideal, however. Boron addition suppressed coking but did so by weakening the ethylene binding so much that that it all simply desorbed at low temperatures, and the loss of strong chemisorption sites would likely make the clusters useless for catalysis of reactions such as alkane-to-alkene conversion. Tin addition stabilized the clusters against coking and sintering, however, because the Sn:Pt stoichiometry was high, the numbers of strong chemisorption sites per cluster, while stable, were substantially smaller than for equivalent size Ptn clusters.