title: Spin conservation accounts for aluminum cluster anion reactivity pattern with O2.
abstract: The reactivity pattern of small (approximately 10 to 20 atoms) anionic aluminum clusters with oxygen has posed a long-standing puzzle. Those clusters with an odd number of atoms tend to react much more slowly than their even-numbered counterparts. We used Fourier transform ion cyclotron resonance mass spectrometry to show that spin conservation straightforwardly accounts for this trend. The reaction rate of odd-numbered clusters increased appreciably when singlet oxygen was used in place of ground-state (triplet) oxygen. Conversely, monohydride clusters AlnH-, in which addition of the hydrogen atom shifts the spin state by converting formerly open-shell structures to closed-shell ones (and vice versa), exhibited an opposing trend: The odd-n hydride clusters reacted more rapidly with triplet oxygen. These findings are supported by theoretical simulations and highlight the general importance of spin selection rules in mediating cluster reactivity.
authors.affiliation: Institute of Inorganic Chemistry, University of Karlsruhe (TH), 76128 Karlsruhe, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Burgert
authors.forename: H
authors.initials: H
authors.lastname: Schnöckel
authors.forename: A
authors.initials: A
authors.lastname: Grubisic
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: S T
authors.initials: ST
authors.lastname: Stokes
authors.forename: K H
authors.initials: KH
authors.lastname: Bowen
authors.forename: G F
authors.initials: GF
authors.lastname: Ganteför
authors.forename: B
authors.initials: B
authors.lastname: Kiran
authors.forename: P
authors.initials: P
authors.lastname: Jena