Binding energies of palladium carbonyl cluster anions: Collision-induced dissociation of Pd3(CO)n− (n=0–6)

The bond dissociation energies of palladium trimer anion, Pd3−, and its carbonyls, Pd3(CO)n− (n=1–6), are measured in the gas phase by the energy-resolved collision-induced dissociation method. The values obtained are D0(Pd2−−Pd)=2.26±0.36 eV for the bare cluster and D0(Pd3(CO)n−1−−CO)=1.78±0.32 eV, 1.74±0.22 eV, 1.47±0.22 eV, 1.13±0.15 eV, 1.11±0.15 eV, and 1.14±0.17 eV for n=1–6, respectively, for the carbonyls. The results show a general decrease of the bond energy with an increasing number of carbonyls, with two relatively stable structures, Pd3(CO)2− and Pd3(CO)6−. A symmetric Pd3(CO)2− structure with two three-fold bridged carbonyls is postulated.