title: Estimation of σ- and π-donor properties of heterocyclic thioamides by spectroscopic and magnetic resonance methods.
abstract: The charge-transfer complexes (CTC) of few thioamide: 1-methylimidazoline-2-thione (MMI), 3-methyl-1-ethoxycarbonilimidazoline-2-thione (Carb), 5-methylbenzimidazoline-2-thione (BIZ), benzothiazoline-2-thione (BTZ), benzoxazoline-2-thione (BOZ) as σ-donors and diiodine as σ-acceptor were studied by spectroscopic methods (UV/Vis, (1)H NMR). CTC formation constants of thioamides with diiodine were determined using the function of the average-iodine number. The charge-transfer complexes of thioamides as π-donors with tetracyanoethylene (TCNE) as π-electron acceptor, were studied by UV-spectroscopy in dichloromethane and chloroform solutions. The mechanism of interaction MMI and Carb with TCNE have been studied by EPR spectroscopy. Spectral characteristics and formation constants are discussed in the terms of electron donor affinity of thioamides and the nature of the organic solvent used. The ionization potentials of donors were estimated from the CT transition energies of their complexes. The photolytic equilibrium constants of five thioamides are determined using pH-metric titrations.
authors.affiliation: Department of Chemistry, Southern Federal University, Rostov-on-Don 344090, Russia. chernov@sfedu.ru
authors.forename: Margarita S
authors.initials: MS
authors.lastname: Chernov'yants
authors.forename: Evgeniy V
authors.initials: EV
authors.lastname: Khohlov
authors.forename: Gennadiy I
authors.initials: GI
authors.lastname: Bondarenko
authors.forename: Igor V
authors.initials: IV
authors.lastname: Burykin
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry / Q000494:pharmacology; D002725:Chloroform / Q000737:chemistry / Q000494:pharmacology; D004579:Electron Transport / Q000502:physiology; D004583:Electrons; D005030:Ethylenes / Q000737:chemistry / Q000494:pharmacology; D006571:Heterocyclic Compounds / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008954:Models, Biological; D009570:Nitriles / Q000737:chemistry / Q000494:pharmacology; D012997:Solvents / Q000737:chemistry / Q000494:pharmacology; D013057:Spectrum Analysis / Q000379:methods; D055672:Static Electricity; D013854:Thioamides / Q000737:chemistry*
chemical_list: D052160:Benzothiazoles; D005030:Ethylenes; D006571:Heterocyclic Compounds; D009570:Nitriles; D012997:Solvents; D013854:Thioamides; C058836:benzothiazoline; D002725:Chloroform; C003393:tetracyanoethylene