Abstract
In the present study we have performed electron collision experiments with copper carboxylate complexes: [Cu(2)(t-BuNH(2))(2)(µ-O(2)CC(2)F(5))(4)], [Cu(2)(s-BuNH(2))(2)(µ-O(2)CC(2)F(5))(4)], [Cu(2)(EtNH(2))(2)(µ-O(2)CC(2)F(5))(4)], and [Cu(2)(µ-O(2)CC(2)F(5))(4)]. Mass spectrometry was used to identify the fragmentation pattern of the coordination compounds produced in crossed electron - molecular beam experiments and to measure the dependence of ion yields of positive and negative ions on the electron energy. The dissociation pattern of positive ions contains a sequential loss of both the carboxylate ligands and/or the amine ligands from the complexes. Moreover, the fragmentation of the ligands themselves is visible in the mass spectrum below m/z 140. For the studied complexes the metallated ions containing both ligands, e.g., Cu(2)(O(2)CC(2)F(5))(RNH(2))(+), Cu(2)(O(2)CC(2)F(5))(3)(RNH(2))(2)(+) confirm the evaporation of whole complex molecules. A significant production of Cu(+) ion was observed only for [Cu(2)(µ-O(2)CC(2)F(5))(4)], a weak yield was detected for [Cu(2)(EtNH(2))(2)(µ-O(2)CC(2)F(5))(4)] as well. The dissociative electron attachment processes leading to formation of negative ions are similar for all investigated molecules as the highest unoccupied molecular orbital of the studied complexes has Cu-N and Cu-O antibonding character. For all complexes, formation of the Cu(2)(O(2)CC(2)F(5))(4)(-•) anion is observed together with mononuclear DEA fragments Cu(O(2)CC(2)F(5))(3)(-), Cu(O(2)CC(2)F(5))(2)(-) and Cu(O(2)CC(2)F(5))(-•). All dominant DEA fragments of these complexes are formed through single particle resonant processes close to 0 eV.