| Abstract
| - Collision-induced dissociation of complexes of Cu+ bound to a variety of N-donor ligands (N-L) with Xe isstudied using guided ion beam tandem mass spectrometry. The N-L ligands examined include pyridine, 4,4-dipyridyl, 2,2-dipyridyl, and 1,10-phenanthroline. In all cases, the primary and lowest-energy dissociationchannel observed corresponds to the endothermic loss of a single intact N-L ligand. Sequential dissociationof additional N-L ligands is observed at elevated energies for the pyridine and 4,4-dipyridyl complexescontaining more than one ligand. Ligand exchange processes to produce Cu+Xe are also observed as minorreaction pathways in several systems. The primary cross section thresholds are interpreted to yield 0 and 298K bond dissociation energies (BDEs) after accounting for the effects of multiple ion-neutral collisions, thekinetic and internal energy distributions of the reactants, and dissociation lifetimes. Density functional theorycalculations at the B3LYP/6-31G* level are performed to obtain model structures, vibrational frequencies,and rotational constants for the neutral N-L ligands and the Cu+(N-L)x complexes. The relative stabilities ofthe various conformations of these N-L ligands and Cu+(N-L)x complexes as well as theoretical BDEs aredetermined from single point energy calculations at the B3LYP/6-311+G(2d,2p) level of theory using B3LYP/6-31G* optimized geometries. Excellent agreement between theory and experiment is observed for allcomplexes containing one or two N-L ligands, while theory systematically underestimates the strength ofbinding for complexes containing more than two N-L ligands. The ground-state structures of these complexesand the trends in the sequential BDEs are explained in terms of stabilization gained from sd-hybridizationand repulsive ligand−ligand interactions. The nature of the binding interactions in the Cu+(N-L)x complexesare examined via natural bond orbital analyses.
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