Gas phase photodissociation of MC2H2+ (M = Zr, Nb). Determination of D0(M+C2H2

Gas phase photodissociation of M(acetylene)+ where M = Nb, Zr is studied with Fourier transform ion cyclotron resonance mass spectrometry to determine metal ion-ligand bond energies. These ions are generated by the dehydrogenation reaction of thermalized metal ions with ethylene and stored in the trapping cell for photodissociation experiments. From the photoappearances thresholds of the simple cleavage product M+, experimental bond energy values of D0(Zr+C2H2) = 59 ± 3 kcal/mol and D0(Nb+C2H2) = 57 ± 3 kcal/mol are assigned. These energies can be compared to recent theoretical values of De(Zr+C2H2 = 68 kcal/mol and De(Nb+C2H2_) = kcal/mol.