Electronic States and Spin Characterization of Polyanionic High-Spin Molecules and Clusters Derived from 1,3-Dibenzoylbenzene Derivatives as Studied by ESR/Electron Spin Transient Nutation Spectroscopy

Abstract

The systems under study were 1,3-dibenzoyl benzene (1), its methyl derivatives (2,3), and 2,6-dibenzoyl pyridine (4), all of which have topologically pseudogenerate π-LUMO's. The corresponding dianions are expected to form triplet ground states and the anionic molecular assemblages expected to form polyanionic high-spin clusters. The polyanionic molecules and clusters were generated by chemical reduction and investigated by cw/FT pulsed ESR spectroscopy. Alkali metal-bridged high-spin clusters were identified directly by FT pulsed ESR-based 2D Electron Spin Transient Nutation (2D-ESTN) spectroscopy. We found ground-state quintet, quartet, and triplet dimers originating in the oligoketone with pluri-electron doping. We determined all the zero-field splitting parameters, g-values, and the concentration ratio of the high-spin systems with the help of spectral simulation.

Key Words:

• polyanionic high-spin organic molecules
• polyanionic high-spin cluster
• ESR
• electron spin transient nutation spectroscopy
• topological pseudo degenerate molecular orbital
• heteroatomic perturbation