| Abstract
| - Threshold photoelectron-photoion coincidence spectroscopy has been used to investigate thedissociation kinetics of the manganocene ion, Cp2Mn+ (Cp = η5-cyclopentadienyl). The Cp loss reactionwas found to be extremely slow over a large ion internal energy range. By simulating the measuredasymmetric time-of-flight peak shapes and breakdown diagram, the 0 K thermochemical dissociation limitfor CpMn+ production was determined to be 9.55 ± 0.15 eV. A CpMn+−Cp bond energy of 3.43 eV wasobtained by combining this CpMn+ + Cp dissociation limit with the Cp2Mn adiabatic ionization energy of6.12 ± 0.07 eV. Combining the measured onset with known heats of formation of Cp and Mn+, the Cp−Mn+ bond energy was determined to be 3.38 ± 0.15 eV. These results lead to 298 K heats of formationof Cp2Mn+ and CpMn+ of 863 ± 7 and 935 ± 16 kJ/mol, respectively. Finally, by combining these resultswith a previous measurement of the CpMn(CO)3 → CpMn+ + 3CO + e- dissociation limit, we arrive at anew value for ΔfH°298K(CpMn(CO)3) of −424 ± 17 kJ/mol.
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