Structures of 9,10-dihydro-9-heteroanthracenes and 9,10-dihydro-9-heteroanthracenide anions; an ab initio MO calculation

Abstract

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A Simple and Convenient Method for Generation and NMR Observation of Stable Carbanions: An Advanced Undergraduate Laboratory Experiment

“…The NMR data for potassium xanthenide (10) agree well with those recorded for this salt in liquid ammonia (15) if one allows for the solvent effect. Moreover, we have shown that there is good agreement between the observed 13 C chemical shifts and the calculated (ab initio) charge distributions for a completely flat xanthenide anion and that this species may be classified as an example of an extensively delocalized 16 pi-electron system (16 ). In the case of DHA, treatment of the hydrocarbon with an excess of K + DMSYL-d 6 ᎑ in DMSO-d 6 results in the formation of monoanionic species DHA ᎑ and no DHA 2᎑ is observed.…”

“…4) lacking signals due to the carbanionic centers (carbon C-9). Such signals appear at 68.9 and 72.1 ppm, respectively, in the KNH 2 /NH 3 (ᐉ) system (15,16 ). The disappearance of the carbanionic carbon signal may be explained by considering that such centers, which are deuterated owing to H-D exchange, give rise to weak multiplets (especially for molecules of this size), which may be lost in spectral noise (18).…”

Direct Characterization of Radical Species Generated on One-Electron Oxidation of 3,6-Diamino-10-methylacridan

“…10-Methylacridan and its derivatives are not planar molecules and, according to calculations, may undergo a substantial geometry change after ionization. The B3LYP/6-31G* method predicts that the dihedral angle Φ between two aromatic side rings is 148.11° (compared to 142.7° from HF SCF calculations 14 ) and 149.21° in neutral 3H and 1H , respectively. , The geometry changes on ionization and the resulting radical cations are more planar than their neutral parent compounds: Φ = 161.96° ( 3H • + ) and 165.29° ( 1H • + ).…”