Persistent oxidation dications of dialkyl- and tetraalkyl-perylenes and dibenzo[cd,lm]perylene; charge distribution mode, substituent effects and conformational aspects

Abstract

Starting with appropriate alkylnaphthalenes , 3,10-dimethyl-2, 3,10-diethyl-3, 2,3,10,11-tetramethyl-4 and 3,4,9,10-tetramethyl-perylene 5 were synthesized by a sequence of radical cation and radical anion coupling steps. Persistent oxidation dications of parent perylene 1, alkylperylenes 2-5 and dibenzo[cd,lm]perylene 6 were generated in SbF 5 -SO 2 ClF. Based on 1D-and 2D-NMR experiments combined with AMl calculations the charge delocalization mode in the dications was deduced. The total deshielding ( 13 C), substituent effects, conformational/ geometrical changes and tropicity in the dications are examined.Whereas alkylperylene dications represent 18 electron Hückel dictations with a diamagnetic ring current (more diatropic than their neutral precursors), the 24 (20 periphery) dication of dibenzoperylene exhibits a paramagnetic ring current which greatly shields its protons (more paratropic than neutral hydrocarbon).

Studies on Pyrene and Perylene Derivatives upon Oxidation and Application to a Higher Analogue

“…55 Alkylperylene dications by twoelectron oxidation with SbF 5 /SO 2 ClF were observed in lowtemperature 13 C NMR. 56 Synthesis of 3,9-or 3,10-dibromoperylene was reported in the literature.…”

First Examples of Fluorinated and Chlorinated Polycyclic Aromatic Hydrocarbon (PAH) Dications from Benzo[a]pyrene, Pyrene, and Their Alkyl-Substituted Derivatives

“…28 In our previous studies, we reported on dications from a series of alkyl(cycloalkyl)pyrenes 20 and on alkylperylenes. 19 In relation to our continuing interest in arenium ions and dications derived from different classes of PAHs and the significance of electrophiles derived from carcinogenic PAHs in adduct formation with DNA bases that could lead to cell damage, we report here the first examples of benzo[a]pyrenium dications, 2-6, and pyrenium dications, 7-9. Detailed assignments for parent 1 are also included for comparison.…”

“…Following initial feasibility studies using early, low-field 1 H NMR by Brouwer, 12 many of the subsequent investigations were reported by Olah and associates. [13][14][15][16][17] More recent examples were provided by Michl, 18 Laali, [19][20][21][22] Mu ¨llen, 8,9 and their associates; the topic has been reviewed. 23 Because of the well-established relationship between 13 C NMR chemical shift and charge in structurally analogous ions, it became the primary tool for probing dications.…”

“…On the basis of 13 C, 19 F, and 1 H NMR data, the charge delocalization mode, total deshieldings, one-bond and long-range C-F coupling constants, and tropicity of the systems have been evaluated. The AM1-calculated ∆∆H f °values and carbon charges were also compared.…”

Scalable synthesis of quaterrylene: solution-phase 1H NMR spectroscopy of its oxidative dication

“…26 Our product was further characterized as quaterrylene by a novel NMR technique. The well-known insolubility of high melting crystalline substances such as 4 suggests that NMR spectral characterization should be impossible; however, many arenium ions and arene oxidative dications 38,39 (neutral structure minus two electrons) have been observed in solution [40][41][42][43][44][45][46][47] and we investigated whether protonation might increase solubility and facilitate NMR analysis. Quaterrylene ( 4) is insoluble in dichloroethane (DCE), but with the aid of mild sonication (Scheme 2), we find that small amounts dissolve in 1 M triflic acid-d/DCE-d 4 with formation of a dark blue-green solution.…”