Diastereotopic splitting in the <sup>13</sup>C NMR spectra of sulfur homofullerenes and methanofullerenes with chiral fragments

Tulyabaev, Arthur R.; Tuktarov, Airat R.; Халилов, Л. М.

doi:10.1002/mrc.4027

Cited by 10 publications

(4 citation statements)

References 32 publications

(37 reference statements)

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“…The experimental evidences for the ring currents were NMR highfrequency proton chemical shifts in C 60 H 2 , as well as in some fullerene systems we described earlier. [62] The ring currents also affect 13 C NMR high-frequency and low-frequency chemical shifts in fullerene derivatives, as it was observed in recent works [28,[62][63][64] .…”

Section: R E S U L T S a N D Discussionmentioning

confidence: 83%

“…Using the GIAO‐PBE/3z method, we have performed earlier full 13 C NMR assignments for the C S spiro‐cycloalkylidenehomo‐ and C 2V methanofullerenes, C 1 chiral spiro‐cycloadducts, and those with sulphur atoms in attached fragments, аs well as for C 2V N ‐substituted aziridinofullerenes . An accuracy of the method was assessed on the basis of calculations of 1 H and 13 C NMR CSs for simple organic compounds and a series of fullerene derivatives, whose structure was unequivocally determined with the NMR INADEQUATE technique …”

Section: Introductionmentioning

confidence: 99%

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Are there reliable DFT approaches for ¹³C NMR chemical shift predictions of fullerene C₆₀ derivatives?

Tulyabaev

Kiryanov

Samigullin

et al. 2016

Int J of Quantum Chemistry

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The relationships between experimental and theoretical 13C NMR chemical shifts of a pristine fullerene C60, monoadducts from [2 + n] cycloaddition (n = 1–3), and one [2 + 1] bis‐adduct are systematically analyzed for the first time by using diverse quantum‐chemical levels of theory. These levels involved B3LYP, B3PW91, B97‐2, mPW1PW91, PBE1PBE, and X3LYP hybrid functionals combined with 3‐21G, 6‐31G, 6‐31G(d), 6‐31G(d,p), 6‐31G(d,2p), LanL2DZ, and SDDAll basis sets. X3LYP/6‐31G approach is determined to have the lowest deviations from the 13C NMR experimental data compared to the other methods for all the fullerene compounds (mean absolute error value is 0.856 ppm and root mean squared error value is 1.197 ppm). The highest deviations are characteristic for α (sp2 C2/C5/C8/C10) and β (sp2 C6/C7/C11/C12) carbon atoms relative to a functionalization site and for those (sp3 C1/C9) directly attached with a side fragment in the [2 + n] monoadducts (n = 1–3). A probable reason of such deviation is that the approaches do not take into account a contribution of paramagnetic ring currents to 13C NMR chemical shifts. The results will be useful in design of novel fullerene derivatives and in performing unambiguous 13C NMR chemical shift assignments with modern quantum chemistry calculations.

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Section: R E S U L T S a N D Discussionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Are there reliable DFT approaches for ¹³C NMR chemical shift predictions of fullerene C₆₀ derivatives?

Tulyabaev

Kiryanov

Samigullin

et al. 2016

Int J of Quantum Chemistry

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“…Accordingly, a tool, Schlegel diagrams, used for the IUPAC naming of diamondoids (and other polycyclic hydrocarbons) is also a tool for assessing NMR data of polycyclics, e.g. for hydrogenated fullerenes . Schlegel diagrams for each of the tetramantanes are shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…for hydrogenated fullerenes. [59] Schlegel diagrams for each of the tetramantanes are shown in Fig. 3 and discussed in the succeeding text.…”

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confidence: 99%

NMR spectral properties of the tetramantanes – nanometer‐sized diamondoids

Balaban

Young

Plavec

et al. 2015

Magnetic Reson in Chemistry

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Tetramantanes, and all diamondoid hydrocarbons, possess carbon frameworks that are superimposable upon the cubic diamond lattice. This characteristic is invaluable in assigning their (1)H and (13)C NMR spectra because it translates into repeating structural features, such as diamond-cage isobutyl moieties with distinctively complex methine to methylene signatures in COSY and HMBC data, connected to variable, but systematic linkages of methine and quaternary carbons. In all tetramantane C22H28 isomers, diamond-lattice structures result in long-range (4)JHH, W-coupling in COSY data, except where negated by symmetry; there are two highly symmetrical and one chiral tetramantane (showing seven (4)JHH). Isobutyl-cage methines of lower diamondoids and tetramantanes are the most shielded resonances in their (13)C spectra (<29.5 ppm). The isobutyl methylenes are bonded to additional methines and at least one quaternary carbon in the tetramantanes. W-couplings between these methines and methylenes clarify spin-network interconnections and detailed surface hydrogen stereochemistry. Vicinal couplings of the isobutyl methylenes reveal positions of the quaternary carbons: HMBC data then tie the more remote spin systems together. Diamondoid (13) C NMR chemical shifts are largely determined by α and β effects, however γ-shielding effects are important in [123]tetramantane. (1)H NMR chemical shifts generally correlate with numbers of 1,3-diaxial H-H interactions. Tight van der Waals contacts within [123]tetramantane's molecular groove, however, form improper hydrogen bonds, deshielding hydrogen nuclei inside the groove, while shielding those outside, indicated by Δδ of 1.47 ppm for geminal hydrogens bonded to C-3,21. These findings should be valuable in future NMR studies of diamondoids/nanodiamonds of increasing size.

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Observation of Diastereotopic Signals in ¹⁵N NMR Spectroscopy

2015

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The first example in the literature of ac ompound showing anisochronous 15 Na toms resulting from diastereotopicity is described. Racemic 1,3-dimethyl-2-phenyloctahydro-1H-benzimidazole was prepared and studied by 1 H, 13 Ca nd 15 NNMR spectroscopy. If convenient conditions were used (monitored by theoretical calculations of 2 J N-H spin-spin coupling constants), two 15 NNMR signals were observed and corresponded to the diastereotopic atoms.GIAO/density-functional calculations of chemical shifts were not only in good agreement with the experimental values but also served as prediction tools.T his study suggests that 15 NNMR spectroscopycould be used to probe chirality.

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Diastereotopic splitting in the ¹³C NMR spectra of sulfur homofullerenes and methanofullerenes with chiral fragments

Cited by 10 publications

References 32 publications

Are there reliable DFT approaches for ¹³C NMR chemical shift predictions of fullerene C₆₀ derivatives?

Are there reliable DFT approaches for ¹³C NMR chemical shift predictions of fullerene C₆₀ derivatives?

NMR spectral properties of the tetramantanes – nanometer‐sized diamondoids

Observation of Diastereotopic Signals in ¹⁵N NMR Spectroscopy

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Diastereotopic splitting in the 13C NMR spectra of sulfur homofullerenes and methanofullerenes with chiral fragments

Cited by 10 publications

References 32 publications

Are there reliable DFT approaches for 13C NMR chemical shift predictions of fullerene C60 derivatives?

Are there reliable DFT approaches for 13C NMR chemical shift predictions of fullerene C60 derivatives?

NMR spectral properties of the tetramantanes – nanometer‐sized diamondoids

Observation of Diastereotopic Signals in 15N NMR Spectroscopy

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Diastereotopic splitting in the ¹³C NMR spectra of sulfur homofullerenes and methanofullerenes with chiral fragments

Are there reliable DFT approaches for ¹³C NMR chemical shift predictions of fullerene C₆₀ derivatives?

Are there reliable DFT approaches for ¹³C NMR chemical shift predictions of fullerene C₆₀ derivatives?

Observation of Diastereotopic Signals in ¹⁵N NMR Spectroscopy