Isolation and Structure of [(Fluorenone ⊙⊖){Na⊕(dme)₂}]₂—a Touchstone for Radical Contact Ion Pairs?

Abstract

Single crystals of a radical ion pair salt—the title compound—could be grown after stoichiometric reduction of fluorenone with sodium in aprotic solution under argon at –50°C. The structure determination reveals that a dimeric contact ion pair containing an Na2O2 four‐membered ring is present and shows, for the first time, the bonding between radical anions and countercations: The solvated Na⊕ ion is situated above the plane of the molecule and outside of the πCO plane. This finding further supports the assumption of a π spin delocalization from the radical anion to the metal cation, as derived from the positive ENDOR metal couplings of radical ion pairs in solution.

Single‐Crystal Structure of the Solvent‐Separated Radical Ion Pair [9,10‐diphenylanthracene.⊖][Na⊕(THF)6] and its implication for cation solvation

“…In summary, a comparison of the single-crystal structures of both 9,lO-diphenylanthracene and its radical anion do not exhibit large specific differences characteristic for the insertion of an additional electron. Due to the delocalization of the negative charge over the 14-center 7c system, no preferential site for the formation of a contact radical ion pair [7] results, and, therefore, the sodium metal reduction product crystallizes with a solvent-separated counter cation.…”

Cobalt and Iron Stabilized Ketyl, Ketiminyl and Aldiminyl Radical Anions

“…Details concerning the syntheses of all complexe, the spectroscopic and physical properties, in situ spectroscopic data and X-ray diffraction data are given in the Supporting Information. Deposition Numbers 2093093 ([K{18c6}][1]), 2093094 ([K{18c6}] [2]), 2093095 (K {18c6} [3]), 2093096 (K{18c6}[4]), 2093097 (K{18c6} [5]), 2093086 (1), 2093087 (2), 2093088 (5), 2093089 (6), 2093090 (7), 2093091 (8), 2093098 (K{18c6} [9]), 2093099 ([K{18c6}] 2 [10]), 2093100 ([K {18c6}] 2 [11]), 2093092 (K{18c6} [12]) contain the supplementary crystallographic data for this paper. These data are provided free of charge by the joint Cambridge Crystallographic Data Centre and Fachinformationszentrum Karlsruhe Access Structures service.…”

“…However, examples for metal-bound carbonyl or iminyl radical anions are scarce and mostly restricted to diaryl ketones as illustrated for the isolation of the alkali metal salts the benzophenone or fluorenone radical anion. [7,8] Few additional examples of other metal complexes bearing simple diaryl ketyl or fluorenyl radical anions were authenticated in case of transition-(Fe, Zr) [9][10][11] and rare earth metals (Sm, Eur, Yb, La) [12,[13][14][15][16] as well as uranium [17] and alkali (earth) metals. [18,19] Here, the intermolecular coupling of the substrate occurs in the absence of sufficient steric protection or blocking of susceptible substrate positions, which in rare cases is found to be reversible.…”

Organic polyanionic high-spin molecular clusters: topological-symmetry controlled models for organic ferromagnetic metals

“…Thus, we have checked the reliability of the calculations in carefully choosing a real molecular system with its molecular/crystal structure well determined by X-ray analysis, i.e., [Fluorenone À {Na + (dme) 2 }] 2 , where ''dme'' denotes dimethoxyethane. 16…”

“…13,14 Recently, polyanionic high-spin molecular clusters with the spin multiplicities up to septet have been published for alkaline metal cation bridged polyanionic fullerene. 15 Interestingly, from the view point of molecular-spin functionalities in the solid state, the crystallizations of anionic organic/aromatic molecules have successfully been achieved for monoanionic fluorenone, 16 trianionic decacyclene 17 and tetraanionic rubrene. 18 In this work, we report for the first time experimental evidence of oligoketone-based polyanionic high-spin molecular clusters with S = 1, 3/2, and 2 and their clustering structures in the ground state.…”