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Search for "dication" in Full Text gives 54 result(s) in Beilstein Journal of Organic Chemistry.
Metal-free hydroarylation of the side chain carbon–carbon double bond of 5-(2-arylethenyl)-3-aryl-1,2,4-oxadiazoles in triflic acid
Beilstein J. Org. Chem. 2017, 13, 883–894, doi:10.3762/bjoc.13.89
- system (formation of dication E) or at the carbon Cα of the side chain C=C double bond (formation of dications B or D). Finally, the third protonation giving rise to trication F is rather high in energy (ΔG298 121 kJ/mol for E→F) and therefore highly unlikely. Also the outlined route leading to species B
- is energetically unfavorable (ΔG298 = −40.3 + 66.7 = 26.4 kJ/mol) and the formation of this dication is not expected. In contrast, the generation of dication D should be possible (ΔG298 = −59.2 + 52.4 = −6.8 kJ/mol). Despite more negative values of ΔG298 calculated for the formation of the N2,N4
- -diprotonated form D. The calculated electronic characteristics of species A–F revealed that the dication D has the highest electrophilicity index ω (7.48 eV) among the other cationic species, even including trication F (Table 1). Therefore, dication D is expected to be an extremely reactive electrophile
Superelectrophilic activation of 5-hydroxymethylfurfural and 2,5-diformylfuran: organic synthesis based on biomass-derived products
Beilstein J. Org. Chem. 2016, 12, 2125–2135, doi:10.3762/bjoc.12.202
- protonation of the carbonyl oxygen and hydroxy group of 5-HMF (1a) in strong acids gives rise to cationic species A, the dehydration of the latter may result in the formation of heteroaromatic benzyl-type dication B (Scheme 1). Protonation of the aldehyde groups in 2,5-DFF (2) leads to cation C and dication D
- cationic species are collected in Table 2 (see spectral figures in Supporting Information File 1). The spectral data clearly prove that protonation of 1a in TfOH gives rise to dication A (Scheme 1). Thus, in the 13C NMR spectrum the signal at δ 67.5 ppm belongs to the protonated hydroxymethyl group CH2O+H2
- calculations (vide supra). According to the NMR data (Table 2 and Supporting Information File 1) protonation of 2 in TfOH leads to the O,O-diprotonated species D. Analogous to dication A, a down-field shift of signals of protons and carbons of the furan ring in 1H and 13C NMR spectra of D compared to the
Reactions of N,3-diarylpropiolamides with arenes under superelectrophilic activation: synthesis of 4,4-diaryl-3,4-dihydroquinolin-2(1H)-ones and their derivatives
Beilstein J. Org. Chem. 2016, 12, 950–956, doi:10.3762/bjoc.12.93
- , perhaps, dication D1 was not reactive due to the bigger spatial volume of the methyl substituent in the N-acyl group compared to hydrogen of the N-formyl one in C1, that hampered the reaction with arene molecule. Conclusion A simple and effective approach to 4,4-diaryl-3,4-dihydroquinolin-2-(1H)-ones
Urethane tetrathiafulvalene derivatives: synthesis, self-assembly and electrochemical properties
Beilstein J. Org. Chem. 2015, 11, 2343–2349, doi:10.3762/bjoc.11.255
- the dication (TTF2+) (Figure 6). Both the first-wave and the second-wave oxidation potentials of T2 were higher (15 mV) than those of T1, which indicated that introduction of another urethane group resulted in a decrease of the electron-donating ability. Cyclic voltammograms were also measured to
Polythiophene and oligothiophene systems modified by TTF electroactive units for organic electronics
Beilstein J. Org. Chem. 2015, 11, 1749–1766, doi:10.3762/bjoc.11.191
- as reversible redox systems with low potentials of oxidation to cation radical and dication species. The high level of stability observed for the oxidised TTF π-electron system arises from the aromatic nature of the oxidised 1,3-dithiolium rings and this has triggered tremendous efforts directed
- and cathodic runs, was evident for all polymers, but clearest for 6c. This was assigned to the formation of a mixed valence state and aggregated cation radical [50]. The relative increase in the peak current during oxidation to the dication, compared to that of cation radical formation, was explained
- formation of TTF cation radical and dication were not apparent in the CV of the film, but were discernible in solution state. Pure 13e, and 13e with a small amount of the parent poly(3,3'''-didodecyl-2,2':5',2'':5'',2'''-quaterthiophene) (PQT12) (5 or 10 wt %), did not exhibit any OFET activity due to hole
Grubbs–Hoveyda type catalysts bearing a dicationic N-heterocyclic carbene for biphasic olefin metathesis reactions in ionic liquids
Beilstein J. Org. Chem. 2015, 11, 1632–1638, doi:10.3762/bjoc.11.178
- ), 1491 (m), 1251 (m), 1152 (m), 1114 (m), 1028 (s), 923 (m), 840 (s), 801 (s), 754 (s), 637 (s), 572 (s), 517 (s) cm-1; MS (ESI) m/z: calcd. for C35H50Cl2N4ORu (dication, z = 2): 357.1199, found: 357.1214; m/z calcd. for C36H50F3Cl2N4O4RuS: 863.1923, found: 863.1905. Crystals suitable for X-ray
Tetrathiafulvalene chemistry
Beilstein J. Org. Chem. 2015, 11, 1528–1529, doi:10.3762/bjoc.11.167
- reversible process to the corresponding aromatic cation radical and dication species, according to two successive one-electron redox processes. This excellent π-donating ability, coupled to the high stability of both oxidized species, has contributed to the establishment of this unit as a key contemporary
Tetrathiafulvalene-based azine ligands for anion and metal cation coordination
Beilstein J. Org. Chem. 2015, 11, 1379–1391, doi:10.3762/bjoc.11.149
- ; tetrathiafulvalene; X-ray; Introduction Tetrathiafulvalene (TTF) is known to have excellent electron-donating properties resulting in stable radical cation (TTF•+) and dication (TTF2+) species from two sequential and reversible oxidation processes. The huge interest in the synthesis of TTF and its very numerous
Selected synthetic strategies to cyclophanes
Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142
- monocation, dication, and dianion of substantial stability. Riccardin C (96) is a macrocyclic bis-bibenzyl entity with pharmacological properties, including antimycotic and antibacterial effects, and cytotoxicity against P-388 mouse leukaemia and KB cell lines from nasopharyngeal carcinoma. In view of these
Advances in the synthesis of functionalised pyrrolotetrathiafulvalenes
Beilstein J. Org. Chem. 2015, 11, 1112–1122, doi:10.3762/bjoc.11.125
- been utilized in the formation of charge-transfer (CT) complexes for more than 40 years [21][22][23]. TTF (1) (Figure 1) is not aromatic according to the Hückel definition as its 14 π-electrons lack cyclic conjugation. Upon oxidation to the radical cation (2) and dication (3) states, a gain in
- materials with applications in supramolecular chemistry, molecular electronics and as sensors. The sequential, reversible oxidation of TTF (1) to its stable radical cation (2) and dication (3) states. Structures and possible substitution positions of MPTTFs (4) and BPTTFs (5). Large-scale synthesis of 6
Regioselective synthesis of chiral dimethyl-bis(ethylenedithio)tetrathiafulvalene sulfones
Beilstein J. Org. Chem. 2015, 11, 1105–1111, doi:10.3762/bjoc.11.124
- conformation. Cyclic voltammetry measurements indicate fully reversible oxidation in radical cation and dication species. Keywords: chirality; crystal structures; molecular materials; sulfones; tetrathiafulvalenes; Introduction Chiral tetrathiafulvalene (TTF) derivatives have been addressed for the first
- generated lose oxygen to afford BEDT-TTF. However, in strike contrast with the behavior of the latter, cyclic voltammetry measurements for (R,R)-1 and (S,S)-1 show reversible two single-electron oxidation processes into radical cation and dication species at ΔE1/2 = +0.67 and 1.00 V vs SCE, respectively
Single-molecule conductance of a chemically modified, π-extended tetrathiafulvalene and its charge-transfer complex with F4TCNQ
Beilstein J. Org. Chem. 2015, 11, 1068–1078, doi:10.3762/bjoc.11.120
- -dithiol-2-ylidene)-9,10-dihydroanthracene) which, in contrast to pristine TTF that exhibits two oxidation peaks to form the radical cation and dication species, shows only one oxidation peak involving a two electron process to form the dication state. Furthermore, the geometrical properties of exTTF are
- with that of the exTTF unit. Similar to pristine exTTF, the new exTTF derivative 5 exhibited only one quasi-reversible oxidation peak, involving a two-electron process to form the dication state [25][26]. This oxidation peak appears at Epa = 217 mV (ΔE = 285 mV, peak-to-peak separation), which is quite
- ]. However, it is well known that the cationic (1+) state of exTTF is less thermodynamically stable than the dication (2+) [34], resulting in inverted oxidation potentials of the cation and dication. Additionally, it is known that the resonance between the neutral and dication is impossible due to the strong
Glycoluril–tetrathiafulvalene molecular clips: on the influence of electronic and spatial properties for binding neutral accepting guests
Beilstein J. Org. Chem. 2015, 11, 1023–1036, doi:10.3762/bjoc.11.115
- = +0.65 V vs Fc+/Fc corresponding to the successive generation of cation radical then dication species simultaneously on each TTF framework (Figure 3). This unique first two-electron oxidation step indicates that the two TTF units are electrochemically equivalent, thus excluding the presence of intra- or
- characteristic for the cation radical and/or the π-dimer (440, 595 nm), bands which are characteristic for substituted TTF derivatives. After addition of nearly two equivalents of oxidizing reagent, we noted the appearance of the absorption band characteristic of the formation of the TTF dication (340 nm). As
Interactions between tetrathiafulvalene units in dimeric structures – the influence of cyclic cores
Beilstein J. Org. Chem. 2015, 11, 930–948, doi:10.3762/bjoc.11.104
- two TTF dication units. This splitting is seen more clearly in the differential pulse voltammograms (Supporting Information File 1, Figure S3). We note that for the SEt derivative of compound 4, measured under different conditions by Iyoda and co-workers (in PhCN, Bu4NClO4), only two two-electron
- −1 used for these studies, the reversibility remains unchanged confirming the high stability of the formed radical cation and dication states within each TTF redox site (in further text defined as “polaron” and “bipolaron” states, respectively; see Scheme 4). The small peak separation, ΔE, between
- in the concentrated and in the diluted solutions. This suggests that the doubly charged structures 4 and 5 are in the form of a spinless dication, represented by the two interacting intrachain polarons. Obviously, the optical spectra of interchain π-dimers of short oligomers are characterized by two
Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions
Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96
- the second to the dication. Non-substituted derivative 4c shows a lower first oxidation potential than its alkylS-substituted counterpart 4a,b, as expected due to the electron-withdrawing effect of the two thioalkyl groups [28][29]. The strong electron-withdrawing effect of the 4-nitrophenyl group in
Copper ion salts of arylthiotetrathiafulvalenes: synthesis, structure diversity and magnetic properties
Beilstein J. Org. Chem. 2015, 11, 850–859, doi:10.3762/bjoc.11.95
- –, and coexistence of planar [Cu(II)Br4]2– and tetrahedral [Cu(II)Br3]– ions. On the other hand, the TTFs show either radical cation or dication states that depend on their redox potentials. The central TTF framework on most of TTFs is nearly planar despite the charge on them, whereas the two dithiole
- conformation similar to its neutral state, whereas the spatial alignment of the 4-tolyl groups is altered (Figure S6 in Supporting Information File 1). The calculated δ value of 3 in the salt is 0.604, indicating that 3 is oxidized to the dication form. The inorganic component CuBr4 has a planar conformation
- of molecule 5 and half of Cu2Br6 crystallographically independent (Figure 4a). The central TTF core of 5 adopts the planar conformation, and the δ value of 5 in the salt is 0.595, indicating that 5 is oxidized to the dication form. As for the inorganic component Cu2Br6, two Cu atoms are connected by
Molecular ordering at electrified interfaces: Template and potential effects
Beilstein J. Org. Chem. 2014, 10, 2243–2254, doi:10.3762/bjoc.10.233
- /P1’ and P3/P3’) [5][6][7][13][14][15][16], as well as to an order/disorder phase transition due to chloride desorption/adsorption [17]. As mentioned in the Introduction, the viologen dication (DBV2+) is known to undergo two successive one-electron transfer steps in the electrochemical environment
- forming first the viologen monocation radical (DBV+•) (Figure 2) and then the uncharged molecule (DBV0) (for details see [5][6][13][14][15][16], and the papers cited therein). While the dication and monocation radicals are soluble in aqueous solutions, the uncharged molecules can accumulate at the
- , or 14.49·1013 molecules/cm2. A more detailed discussion of the molecular arrangement within the herringbone rows is postponed until section Discussion where we will also make a comparison with the corresponding system DBV on Cl/Cu(100). The DBV-dication based herring-bone structure remains stable in
Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition
Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308
- complex (Scheme 8) [131]. In 2008, the group of Donnelly was able to crystallize a dinuclear copper(I)-TBTA complex from TBTA and tetrakis(acetonitrile)copper(I) tetrafluoroborate under anaerobic conditions in acetonitrile [131]. The single crystal X-ray structure shows a dinuclear dication [Cu2(μ-TBTA
An aniline dication-like transition state in the Bamberger rearrangement
Beilstein J. Org. Chem. 2013, 9, 1073–1082, doi:10.3762/bjoc.9.119
- activation energy similar to the experimental one was obtained. A new mechanism of the rearrangement including the aniline dication-like transition state was proposed. Keywords: Bamberger rearrangement; DFT calculations; N-phenylhydroxylamine; proton transfer; reactive intermediates; transition states
- monoprotonated systems would arise from the poor proton-donating strength to the oxygen of the N–O bond in the model of Scheme 5. In order to enhance the donation, a dication system was constructed at the left of Scheme 6. However, the bond-interchange transition state could not be obtained in spite of many
- (III) along with TS2(III, [1,3]-shift). Geometries of TS2(III) and TS2(III, [1,3]-shift) are like those of the aniline dication and (H2O)16. Figure 5 shows the energy change of the reaction in Figure 4. The rate-determining step is TS2, and TS2(III,[1,3]-shift) = +32.20 kcal/mol is much larger than TS2
Hybrid super electron donors – preparation and reactivity
Beilstein J. Org. Chem. 2012, 8, 994–1002, doi:10.3762/bjoc.8.112
- shown. This should then react with an iodoarene 37 to afford the dication salt 38 featuring an aryl anion and an iodide as counterions. In these circumstances, we suggest that the aryl anion can abstract a proton rapidly from the periphery of 38 to form reduced arene 39, consistent with our previous
- studies on deprotonation of pyridinium salts [21]. However, 38 is a dication, and, to attain neutrality, could lose two protons. Compound 3 could be a strong base (in support of this, we have witnessed complete conversion of the analogous donor 2 to form 40 by rapid exchange in CD3CN as solvent; see
- existence is clear from its preparation here by deprotonation of 12 with one equivalent of NaH (see Supporting Information File 1). For protonated forms of other tetraaza donors, see [44][45]). Compound 11 is likely to deprotonate dication 21 analogously to the previous examples. If 43 results from this
Sexithiophenes as efficient luminescence quenchers of quantum dots
Beilstein J. Org. Chem. 2011, 7, 1722–1731, doi:10.3762/bjoc.7.202
- 1b shows two quasi-reversible redox waves consistent with the formation of a polaronic cation at the first step followed by the formation of the dication species at the second oxidation. Compared to 2b, the first oxidation peak of 1b is shifted to a less positive value, viz. from +0.90 V to +0.70 V
- expected to be negligible. During the experiments, no new peaks appeared in either sample until the second oxidation process. At this point, two new peaks emerge above +0.80 V at 668 and >1100 nm for 1b and are assigned to the dication, as are both new peaks in 2b (at 651 and >1100 nm). These continue to
Molecular rearrangements of superelectrophiles
Beilstein J. Org. Chem. 2011, 7, 346–363, doi:10.3762/bjoc.7.45
- steps similar to monocationic rearrangements, such as alkyl group shifts, Wagner–Meerwein shifts, hydride shifts, ring opening reactions, and other skeletal rearrangements. This review will describe these types of superelectrophilic reactions. Keywords: dication; rearrangement; superacid
- example, 2-oxazolines were shown [14] to form products with arenes and a mechanism was proposed involving ring opening of the superelectrophile (13, Scheme 2). The ring opening step effectively separates the positive charge centers, as the superelectrophile isomerizes from a 1,3-dication 13 to a 1,5
- -dication 14. Subsequent reaction with benzene yields the final product. Using the same chemistry, a chiral 2-oxazoline was shown to give a Friedel–Crafts product in modest diastereoselectivity. A similar reaction was reported [15] in the AlCl3-catalyzed reactions of isoxazolidines (Scheme 3). Product
Redox-active tetrathiafulvalene and dithiolene compounds derived from allylic 1,4-diol rearrangement products of disubstituted 1,3-dithiole derivatives
Beilstein J. Org. Chem. 2010, 6, 1002–1014, doi:10.3762/bjoc.6.113
- the thione causes the oxidation to occur at a higher potential in 3 than in 27. In TTF derivative 25 the two characteristic reversible single electron redox waves, arising from the step-wise formation of the TTF radical cation and dication, are seen at +260 mV and +720 mV, respectively. The formation
- of the TTF dication hinders subsequent removal of an electron from the thiophene units, so further oxidations are beyond the electrochemical window of the solvent. Compound 28 is reversibly oxidised to 28+· at −740 mV, within the range seen in other nickel dithiolene complexes. A second single
Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation
Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88
- trifluoromethylthiocopper [106]. Subsequent reaction with aryl halides results in the corresponding trifluoromethylsulfanyl derivatives (Scheme 29). Reduction of bis(perfluoroalkyl)disulfides with tetrakis(dimethylamino)ethylene produces tetrakis(dimethylamino)ethylene dication stabilized perfluoroalkyl thiolates. In
- [35]. Another method of catalytic generation of RF• radicals involves electron-transfer from a nucleophile to a perfluoroalkyl halide, in this case using the dimethyl dipyridinium salt (methylviologen, MV2+) as a catalyst. This dication is initially reduced to a radical cation, which then transfers an
- likely. Homogeneous catalysis by the methyl viologen (MV) [186] supports this. This catalyst can oxidize the radical anion [ArSRF]−• via its dication (MV2+) [200][202], accelerating the last step (Scheme 52). 4.2. Radical perfluoroalkylation Synthetic methods for aryl perfluoroalkyl sulfides via RF
Structure and reactivity in neutral organic electron donors derived from 4-dimethylaminopyridine
Beilstein J. Org. Chem. 2010, 6, No. 73, doi:10.3762/bjoc.6.73
- at the 4 and 4′ positions led to only slight changes in the redox potentials. Keywords: dication; 4-DMAP; electron donor; electron transfer; radical cation; redox; reduction; Introduction Neutral organic compounds 1 and 4–10 (Figure 1) have attracted considerable attention as ground-state electron
- ][7][8][9][10][11][12], but is not strong enough to react with alkyl and aryl halides. The driving force for its oxidation is the attainment of some degree of aromaticity in the formation of its radical cation salt 2 on the loss of one electron, and full aromaticity in its dication salt 3 on loss of
- the two pyridine-derived rings and the nature of the substituents on the 4- and 4′-positions of those pyridine rings were the points of particular interest. TDAE, 5, has been used extensively as a two-electron transfer reagent, and many salts that feature its dication have been analysed by X-ray
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