In this work, we present the fixed-frequency (at 355 nm) negative-ion photoelectron spectrum of Co(C0)2NO-. Analysis of the spectrum yields the electron affinity of Co(C0)2NO; EA[Co(CO)zNO] = 1.73 f 0.03 eV. The lack of extensive vibrational progressions in the spectrum is consistent with the neutral species and the negativeion having similar equilibrium geometries.

An upper bound for the adiabatic electron affinity of cyclopentadienylcobaltdicarbonyl [CpCo(CO)2] is 0.86 ± 0.2 eV as determined by fixed-frequency negative-ion photoelectron spectroscopy. During the course of the experimental work, the generation of the binuclear complex [CpCo(CO)2]2 - is detected, and, to our knowledge, this is the first observation of this anionic cluster. Electronic structural calculations using both the density functional theory formalism and ab initio techniques are completed for both CpCo(CO)2 and the corresponding negative-ion. A DFT/DZVP2 calculation yields the vertical electron affinity of CpCo(CO)2 as 0.84 ± 1.0 eV. The theoretical results confirm that a weak “allyl-ene” type structure exists in the cyclopentadienyl ligand of both molecules, but the distortion is less pronounced in CpCo(CO)2 - than in CpCo(CO)2. Our results lend further support to the classification of CpCo(CO)2 - as a 19-electron complex.

Fixed-frequency negative-ion photoelectron spectra of tricarbonyl(η5-methylcyclopentadienyl)manganate(0), Cp*Mn(CO)3 -, are obtained at 355 and 532 nm. The adiabatic electron affinity of tricarbonyl(η5-methylcyclopentadienyl)manganese(I), Cp*Mn(CO)3, as obtained from the experiments, is 0.5 ± 0.1 eV, and the vertical ionization potential of the anion is 1.0 ± 0.1 eV. By combining our electron affinity results with literature gas-phase acidity estimates for Cp*Mn(CO)3 we determine that the C−H bond dissociation energy, D[H−CH2C5H4Mn(CO)3 -], in the anion is 2.2 ± 0.8 eV.

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