Manganese−Chalcocarbonyl Bond Strengths from Threshold Photoelectron Photoion Coincidence Spectroscopy

Abstract

The dissociation kinetics of CpMn(CO)2CX (X = S, Se) complexes have been investigated by threshold photoelectron photoion coincidence (TPEPICO) spectroscopy. Energy-selected CpMn(CO)2CX+ ions sequentially lose the two carbonyl and chalcocarbonyl ligands upon photoionization. The resulting asymmetric time-of-flight peak shapes and breakdown diagrams were simulated, and the following 0 K appearance energies were determined for the fragment ions: CpMn(CO)CS+, 8.79 ± 0.05 eV; CpMnCS+, 9.42 ± 0.05 eV; CpMn+, 11.53 ± 0.05 eV; CpMn(CO)CSe+, 8.70 ± 0.05 eV; CpMnCSe+, 9.39 ± 0.05 eV; and CpMn+, 12.05 ± 0.05 eV. These values, combined with the adiabatic ionization energies, yield Mn−CO bond energies in CpMn(CO)2CX+ (X = S, Se) and CpMn(CO)CX+ (1.20 ± 0.06, 0.63 ± 0.07 eV and 1.08 ± 0.06, 0.72 ± 0.07 eV, respectively) and Mn−CX bond energies in CpMnCX+ (X = S, Se, 2.12 ± 0.07 and 2.66 ± 0.07 eV, respectively).The 0 K heats of formation of the neutral and ionic species were determined using the heats of formation of...