Synthesis and Characterization of Ion Pairs between Alkaline Metal Ions and Anionic Anti-Aromatic and Aromatic Hydrocarbons with ?-Conjugated Central Seven- and Eight-Membered Rings.

ABSTRACT: The synthesis, isolation and full characterization of ion pairs between alkaline metal ions (Li+, Na+, K+) and mono-anions and dianions obtained from 5H-dibenzo[a,d]cycloheptenyl (C15H11 = trop) is reported. According to Nuclear Magnetic Resonance (NMR) spectroscopy, single crystal X-ray analysis and Density Functional Theory (DFT) calculations, the trop? and trop2-• anions show anti-aromatic properties which are dependent on the counter cation M+ and solvent molecules serving as co-ligands. For comparison, the disodium and dipotassium salt of the dianion of dibenzo[a,e]cyclooctatetraene (C16H12 = dbcot) were prepared, which show classical aromatic character. A d8-Rh(I) complex of trop- was prepared and the structure shows a distortion of the C15H11 ligand into a conjugated 10? -benzo pentadienide unit-to which the Rh(I) center is coordinated-and an aromatic 6? electron benzo group which is non-coordinated. Electron transfer reactions between neutral and anionic trop and dbcot species show that the anti-aromatic compounds obtained from trop are significantly stronger reductants.

SUBMITTER: Bloch J 

PROVIDER: S-EPMC7594067 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature