Observation of promoted C–O bond weakening on the heterometallic nickel–silver: Photoelectron velocity-map imaging spectroscopy of AgNi(CO)n−

We report a joint experimental and theoretical study on heterodinuclear silver–nickel carbonyl clusters: AgNi(CO)n− and AgNi(CO)n (n = 2, 3). The photoelectron spectra and photoelectron angular distribution provide information on the electronic structures and geometries of these complexes. Electron affinities of AgNi(CO)2 and AgNi(CO)3 are measured from the photoelectron velocity-map imaging spectra to be 2.29 ± 0.03 and 2.32 ± 0.03 eV, respectively. The complementary theoretical calculations at the B3LYP level and Franck-Condon simulations are performed to establish their geometrical structures. The C–O stretching modes are activated upon photodetachment and determined to be 2024 and 2028 cm−1 for AgNi(CO)2 and AgNi(CO)3, respectively, which are notably red-shifted with respect to those of corresponding unsaturated binary nickel carbonyls. These findings will shed light on the promoted C–O bond weakening by the introduction of a foreign atom to binary unsaturated TM carbonyl complexes.