Charge-transfer complexes between some S-methylated derivatives of 5,5-dimethyl-2,4-dithiohydantoin and molecular diiodine. A UV-Visible, IR, FT-Raman, and 13C NMR study
✍ Scribed by Franco Cristiani; Francesco A. Devillanova; Alessandra Garau; Francesco Isaia; Vito Lippolis; Gaetano Verani
- Publisher
- John Wiley and Sons
- Year
- 1994
- Tongue
- English
- Weight
- 682 KB
- Volume
- 5
- Category
- Article
- ISSN
- 1042-7163
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✦ Synopsis
Equilibrium constants (K) and thennodynamic parameters for the charge-transfer complexes between diiodine and ~l'-4-S-methyl-5,5-dimethylimidazolidine-2-thione (I), 2-S-methyl-5,5-dirnethylimidazolidine-4-thione 12), and A'-A3-ZS-methyl-4-S-methyl-5,5dimethylimidazolidine (3) have been determined in CHzClz by UV-Visible spectroscopy. Depending on the solvent polarity, compound 2 exists as a A' or A' tau-Comer; both the tautomers are present i n CH2C12.
Compounds 1 and 2 act as good donors (K = 11,000 t 800 and 640 t 2l dm3 mol-', 25"C, respectively) owing to the presence of a thioamidic group in the molecule, whereas i n compound 3, the N-coordination causes a strong reduction of the formation constant (K = 14.6 -t 0.8 dm3 mol-', 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 iodivte, which can be possible only for 1. Additional spectroscopic data (FT-Raman, N M R ) enables a deeper understanding of the mutual interaction between donors and diiodine.