ISSN:
1042-7163
Keywords:
Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Equilibrium constants (K) and thermodynamic parameters for the charge-transfer complexes between diiodine and Δ3-4-S-methyl-5,5-dimethylimidazolidine-2-thione (1), 2-S-methyl-5,5-dimethylimidazolidine-4-thione (2), and Δ1-Δ3-2S-methyl-4-S-methyl-5,5-dimethylimidazolidine (3) have been determined in CH2Cl2 by UV-Visible spectroscopy. Depending on the solvent polarity, compound 2 exists as a Δ1 or Δ2 tautomer; both the tautomers are present in CH2Cl2. Compounds 1 and 2 act as good donors (K = 11,000 ± 800 and 640 ± 21 dm3 mol-1, 25°C, respectively) owing to the presence of a thioamidic group in the molecule, whereas in compound 3, the N-coordination causes a strong reduction of the formation constant (K = 14.6 ± 0.8 dm3 mol-1, 25°C). The high difference between the stability constants of 1 and 2 has been ascribed to an intramolecular hydrogen bonding between NH and the bonded iodine, which can be possible only for 1. Additional spectroscopic data (FT-Raman, NMR) enables a deeper understanding of the mutual interaction between donors and diiodine.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hc.520050502
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