Three polynuclear transition metal carbonyl cluster anions, Ru3Co(CO)(13)(-), Ru6C(CO)(16)(2-), and Ru-6(CO)(18)(2-) have been studied using energy-dependent electrospray ionization mass spectrometry (EDESI-MS) and photodetachment photoelectron spectroscopy (PES). EDESI-MS maps show a simple collision-induced dissociation (CID) process for Ru3Co(CO)(n)(-) by stripping CO down to the metal core. For the doubly charged species, two competing CID channels were observed, viz. loss of neutral CO and loss of CO+e(-). It was found that the parent dianions first lose neutral CO down to n=9, producing a series of dianions, Ru6C(CO)(n)(2-) (n=9-16) and Ru-6(CO)(n)(2-) (n=9-18). For n<9, the dianions become electronically unstable against autodetachment, and singly charged anions, Ru6C(CO)(n)(-) and Ru-6(CO)(n)(-) (n=0-9), were observed. The PES spectra of the dianions show the electron binding energies decrease monotonically as n decreases and become similar to0.0 eV for n=9, in exact agreement with the CID patterns that reflect the electronic instability of the doubly charged metal complexes with n<9. All of the PES spectra show congested features, indicating very high density of low-lying electronic states for the transition metal carbonyl clusters. The electron binding energies of Ru3Co(CO)(n)(-) are similar for n=4-13, but decrease sharply from n=4 to 0. The intramolecular Coulomb repulsion in the dianions was observed to increase with loss of CO, ranging from similar to1.8 eV for Ru6C(CO)(16)(2-) to similar to2.4 eV for Ru6C(CO)(9)(2-).