ChemInform Abstract: 1,2,6‐BENZODIAZINYLS ‐ A NEW TYPE OF FREE RADICAL CONTAINING SULFUR AND NITROGEN

Markovskii, L. N.; Talanov, Vladimir S.; Polumbrik, O. M.; Shermolovich, Yu. G.

doi:10.1002/chin.198217104

Cited by 5 publications

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“…In almost all heterocyclic radicals studied to date, the thioaminyl fragment is a part of a longer, three-or fourmembered array of heteroatoms such as -N-S-S-N-(1a, 35 1b, 28 1c, 28 1d, 59 1e, 28,60 1g 59,61 ), -N-S-N-S-(2d 29,62 ), -N-S-N-(4c, 27 4e, 27 4g, 24 5, 63 10 64 ), -S-N-S-(3a, 62,65 3e, 30 3f, 66,67 5, 63 6h, 68,69 6i, 66 9h, 64 9i, 66 10 64 ), and -N-S-S-(7h, 62,70 7i, 71 11 6 ), as shown in Figure 1. Radicals containing the -S-Nfragment connected directly to the carbon framework are rare, and 8 72 as well as two compounds recently reported by us 23 are the only examples. There have been relatively few parent radicals synthesized and studied in detail.…”

Section: Resultsmentioning

confidence: 99%

Theoretical Analysis of Heteroaromatic Thioaminyl Radicals. Part 1: A Comparison of Ab Initio and Density Functional Methods in Calculations of Molecular Geometry and Isotropic Hyperfine Coupling Constants

Kaszyński

2001

J. Phys. Chem. A

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Molecular parameters of 23 heterocyclic radicals containing the thioaminyl fragment were systematically investigated with ab initio and DFT methods. Several basis sets were used to establish correlations between calculated and experimental geometries and isotropic hyperfine coupling constants. Distribution of spin and charge densities in the radicals was analyzed using the UB3LYP/6-31G* method. The data were subsequently analyzed with an emphasis on the quality of correlation rather than on the absolute accuracy of the calculated values. This resulted in a set of empirical scaling factors relating the calculated and experimental hfcc for cyclic thioaminyl radicals and provided a tool for routine design, structural elucidation, and characterization of new radicals. The protocol is used in the critical analysis of hfcc for several previously reported radicals. A companion paper (ref ) follows in this issue [Kaszynski, P. J. Phys. Chem. A 2001, 105, 7626].

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Section: Resultsmentioning

confidence: 99%

Theoretical Analysis of Heteroaromatic Thioaminyl Radicals. Part 1: A Comparison of Ab Initio and Density Functional Methods in Calculations of Molecular Geometry and Isotropic Hyperfine Coupling Constants

Kaszyński

2001

J. Phys. Chem. A

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“…Attempted Generation of Radical 4 from 5 and 7. Treatment of the 4 H -thiatriazine 5 with lead dioxide/potassium carbonate , or thianthrenium perchlorate/pyridine 2 failed to generate radical 4 (Scheme ), and the starting material was recovered. Negative results were also obtained by initial deprotonation of 5 with NaH followed by reaction of the resulting anion with iodine or silver triflate.…”

Section: Resultsmentioning

confidence: 99%

A New Thiatriazine Isomer: Synthesis, Tautomerism, and Molecular Structure of 3,6-Diphenyl-4H-1,2,4,5-thiatriazine as a Precursor to the 1,2,4,5-Thiatriazinyl Radical

et al. 2000

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The diphenyl derivative of 4H-1,2,4,5-thiatriazine (5) was prepared by oxidative cyclization of 9. The molecular structure of 5, obtained by X-ray diffraction [orthorhombic, Pna2(1), a = 9.7746(13) A, b = 21.692(2) A, c = 5.6580(8) A], compares favorably with that predicted with ab initio calculations. The thiatriazine 5 was used as a precursor to the 3,6-diphenyl-1,2,4,5-thiatriazinyl radical (4) through either oxidation with PbO(2), or conversion to and reduction of sulfiminyl chloride 6 with Ph(3)Sb. The weak ESR quintet (a(N) = 1.03 mT, g = 2.0103) observed in the latter case correlates well with the molecular structure of 4, but the results of DFT calculations are ambiguous. Ab initio calculations show that 4H-1,2, 4,5-thiatriazine (I-4H) is the most stable tautomer and is the second most stable isomer among the six possible thiatriazines. All isomeric thiatriazinyl radicals exhibit similar spin distribution patterns. 1,2,4,5-Thiatriazinyl radical (I-R) is calculated to be 23. 1 kcal/mol less stable than the most stable 1,2,4,6 isomer II-R.

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“…Method A (PbO 2 ) is the most common way to generate thioaminyl radicals from the corresponding N−H compounds, but only modest yields have been observed. ,, The addition of MeCN to the reaction mixture significantly increases the yield of the radicals and works particularly well with AgO, a more potent oxidant (Method C). This effect of MeCN cosolvent on the rate of electron transfer from the substrate to the metal oxide is presumably due to (i) increased polarity of the medium, (ii) more complete deprotonation of the substrate, (iii) coordination of the solvent to silver ions, or (iv) a combination of the above.…”

Section: Discussionmentioning

confidence: 99%

“…Scant literature data shows that four persistent partially chlorinated benzo[1,2,4]thiadiazinyls were generated by oxidation of the corresponding 4 H -thiadiazines 8 or reduction of the appropriate sulfiminyl chlorides. , The radicals were reported to persist for 24 h in solution in the presence of air, but their isolation was not attempted. Despite poucity of data, the reported stability was encouraging and prompted us to investigate this general class of [1,2,4]thiadiazinyls.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Theoretical Studies of Fused-Ring Persistent [1,2,4]Thiadiazinyl Radicals

Zienkiewicz

Kaszyński

2004

J. Org. Chem.

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Five persistent radicals 1a-1e were generated by the oxidation of 4H-[1,2,4]thiadiazines 2a-2e and studied with ESR and UV-vis spectroscopy. Three of the radicals, 1a, 1d, and 1e, were generated in high yields (>90%) using either SO(2)Cl(2)/amine in toluene or AgO/K(2)CO(3) in a toluene/MeCN mixture. Halogenated radicals 1d and 1e were sufficiently stable for chromatographic isolation and vacuum sublimation. The solution stability of the fluorinated 1d was measured at t(1/2) approximately 4 months in the absence of oxygen, and 1e at t(1/2) approximately 40 min in the presence of air. The crystal and molecular structures of 1d were determined by X-ray crystallography showing columns of parallel almost evenly spaced planar heterocycles connected by infinite ...N...S... chains. Cyclic voltammetry of 1d and 1e shows reversible reduction waves at about 0 V and irreversible oxidations at about 1.2 V. Spectral and electrochemical properties of 1 were well reproduced by DFT methods.

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ChemInform Abstract: 1,2,6‐BENZODIAZINYLS ‐ A NEW TYPE OF FREE RADICAL CONTAINING SULFUR AND NITROGEN

Abstract: Die Benzothiadiazine (I) werden durch Dechlorierung mit Natriumpulver in die entsprechenden π‐Radikale (II) übergeführt, die in Benzol oder THF eine Lebensdauer von mehreren Tagen haben.

Cited by 5 publications

References 0 publications

Theoretical Analysis of Heteroaromatic Thioaminyl Radicals. Part 1: A Comparison of Ab Initio and Density Functional Methods in Calculations of Molecular Geometry and Isotropic Hyperfine Coupling Constants

Theoretical Analysis of Heteroaromatic Thioaminyl Radicals. Part 1: A Comparison of Ab Initio and Density Functional Methods in Calculations of Molecular Geometry and Isotropic Hyperfine Coupling Constants

A New Thiatriazine Isomer: Synthesis, Tautomerism, and Molecular Structure of 3,6-Diphenyl-4H-1,2,4,5-thiatriazine as a Precursor to the 1,2,4,5-Thiatriazinyl Radical

Experimental and Theoretical Studies of Fused-Ring Persistent [1,2,4]Thiadiazinyl Radicals

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