Reactions of N-heteroaromatic bases with nitrous acid. Part 9. Kinetics of the nitrosation of 1-methyl-3- and 1-methyl-4-methylaminopyridinium perchlorate in aqueous perchloric acid and 13C nuclear magnetic resonance spectra of 1-methyl-4-alkylamino-substituted pyridinium ions

Kalatzis, Evangelos; Kiriazis, L.

doi:10.1039/p29890000179

Cited by 11 publications

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“…A complete line shape fit 12 to the two site exchange broaden spectra give ∆H q ) 13.23 kcal/mol, ∆S q ) -11.9 cal/(mol‚K), and ∆G q (298.16K) ) 16.9 kcal/mol. The Gibbs free energy of activation at 355 K is nearly identical to that reported (17.6 kcal/mol) for rotation about the nitrogen ring carbon bond in 1-methyl-4-(methylamino)pyridinium perchlorate 13 at the same temperature, suggesting that the pyridinium ion substituent plays little if any steric or electronic role in dictating the magnitude of the rotation barrier. The lack of a steric effect is perhaps not surprising given the nearly perpendicular arrangement (vide infra) of the two pyridinium rings in the dication.…”

Section: Resultssupporting

confidence: 76%

“…The 13 C and 1 H NMRs of 3 2+ both exhibited signals for three magnetically distinct methyl groups. In the 13 C NMR spectrum (CD 3 CN) two peaks for the -N(CH 3 ) 2 groups were observed at 41.10 and 41.19 ppm and a peak for the pyridinium N-CH These results are consistent with a significant contribution of resonance form 3 2+ B to the ground state electronic description of the bipyridinium dication 3 leading to restricted rotation at room temperature around the (CH 3 ) 2 N-pyridinium bond (Figure 3). A contribution of resonance form 3 2+ B is also consistent with the B3LYP/6-31G(d) HOMO (Figure 3), which exhibits significant π-electron density between the -N(CH 3 ) 2 group and the ring carbon.…”

Section: Resultsmentioning

confidence: 99%

“…1 H NMR (400 MHz; D 2 O; ppm): δ 3.19 (s, 6H), 3.25 (s, 6H), 3.66 (s, 6H), 7.00 (dd, J ) 7.7, 3.1 Hz, 2H), 7.07 (d, J ) 3.1 Hz, 2H), 8.11 (d, J ) 7.7 Hz, 2H). 13 C NMR (100 MHz; CD 3 CN; ppm): δ 41.1 (q, J ) 136 Hz), 41.2 (q, J ) 136 Hz), 43.8 (q, J ) 145 Hz), 109.5 (d, J ) 172 Hz), 112.1 (d, J ) 172 Hz), 144.1 (s), 145.8 (d, J ) 188 Hz), 157.6 (s). Anal.…”

Section: Discussionunclassified

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Experimental and Computational Studies of Nuclear Substituted 1,1‘-Dimethyl-2,2‘-Bipyridinium Tetrafluoroborates

et al. 2007

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The synthesis and spectral properties of a new 2,2'-bipyridinium ion, 1,1'-dimethyl-4,4'-(dimethylamino)-2,2'-bipyridinium bis(tetrafluoroborate) are reported. Rotation of the dimethylamino group is slow at room temperature on the 400 MHz 1H and 100 MHz 13C NMR time scales. Complete line shape fit of the dynamically broadened NMR spectra was used to determine the activation barriers for this process. The first complete set of UV-vis spectra for a 2,2'-bipyridinium dication and its one- and two-electron reduced products was reported. TD-DFT calculations were used to help assign the origin of the long wavelength absorptions in these species. The effect of substituents on the energies and conformational potential energy surfaces of all three species were also examined using the B3LYP/6-31G(d) computational method.

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Section: Resultssupporting

confidence: 76%

Section: Resultsmentioning

confidence: 99%

Section: Discussionunclassified

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Experimental and Computational Studies of Nuclear Substituted 1,1‘-Dimethyl-2,2‘-Bipyridinium Tetrafluoroborates

et al. 2007

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“…Substantial double-bond character in the exocyclic carbon-nitrogen bond has been established in 1-methyl-4alkylaminopyridinium cations at room temperature in aqueous solution by means of 13 C NMR measurements. 18 In the latter resonance structure, the encapsulation of the guest by CB[7] would place the positive charges adjacent to the polar carbonyl groups on the portals of the host and stabilize the resonance structure. The contribution of this resonance structure may be seen in the 1 H NMR spectrum upon addition of one equivalent of the host (Scheme 2 and Fig.…”

Section: Resultsmentioning

confidence: 99%

Cucurbit[7]uril host-guest and pseudorotaxane complexes with α,ω-bis(pyridinium)alkane dications

Wyman

Macartney

2009

Org. Biomol. Chem.

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The host molecule cucurbit[7]uril forms very stable host-guest complexes (1:1 and 2:1) and [2]pseudorotaxanes with alpha,omega-bis(pyridinium)alkane dications in aqueous solution. With the dications containing pyridinium, 2- and 3-picolinium, and 4-dimethylaminopyridinium end groups and a hexyl chain, [2]pseudorotaxanes are formed with one equivalent of CB[7] positioned over the central chain. A second equivalent of CB[7] encapsulating one of the end groups results in the translocation of the first CB[7] to the other end group. For the dications with these end groups, the 2:1 host-guest complexes exhibit stability constants which are considerably smaller than the 1:1 values as the result of steric and electronic repulsions between the two CB[7] hosts.

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“…mp 189-191°C [7]} was prepared in 40% yield according to the method described [7]. 4-[(1E)-2-(Dimethylaminoethenyl)]-1-methylpyridinium perchlorate, 2.…”

Section: Methodsmentioning

confidence: 99%

Effect of vinylene and 1,4-phenylene spacers on efficiency of the ground-state intramolecular charge-transfer in enlarged 4-dimethylamino-1-methylpyridinium cations

et al. 2009

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15 N NMR chemical shifts of the exo-and endocyclic nitrogen atoms show how efficient is the ground-state intramolecular charge transfer between these sites in 4-dimethylamino-1-methylpyridinium cation (increased contribution of the quinoid resonance form results in a shielding and deshielding effect of their NMR signals, respectively). As it was anticipated, insertion of vinylene and/or 1,4-phenylene spacers to the cation considerably hinders the ground-state charge transfer. This hypothesis is further supported by an analysis of the C-NMe 2 bond lengths (X-ray data show that spacers elongate this bond). The selected valence angles in the compounds studied are also linearly dependent on d( 15 N endo ) and d( 15 N exo ) values. Although the correlation coefficient for the d( 15 N endo ) versus d( 15 N exo ) dependence is equal to 0.983, decrease of the net charge on one nitrogen atom is not compensated entirely by its increase on another nitrogen atom. This shows that exocyclic nitrogen atom is not the only acceptor of the positive charge in the molecule.The natural population analysis shows that the positive charge is transferred not only to the exocyclic N but also to, e.g., 1-and N-methyl C as well as to C3 and C5 atoms in pyridine ring. Ground-state charge transfer through the p-phenylene moiety was found to be less effective than through the trans-vinylene bridge.

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Reactions of N-heteroaromatic bases with nitrous acid. Part 9. Kinetics of the nitrosation of 1-methyl-3- and 1-methyl-4-methylaminopyridinium perchlorate in aqueous perchloric acid and 13C nuclear magnetic resonance spectra of 1-methyl-4-alkylamino-substituted pyridinium ions

Cited by 11 publications

References 0 publications

Experimental and Computational Studies of Nuclear Substituted 1,1‘-Dimethyl-2,2‘-Bipyridinium Tetrafluoroborates

Experimental and Computational Studies of Nuclear Substituted 1,1‘-Dimethyl-2,2‘-Bipyridinium Tetrafluoroborates

Cucurbit[7]uril host-guest and pseudorotaxane complexes with α,ω-bis(pyridinium)alkane dications

Effect of vinylene and 1,4-phenylene spacers on efficiency of the ground-state intramolecular charge-transfer in enlarged 4-dimethylamino-1-methylpyridinium cations

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