Spin exchange between transition metal complexes and nitroxyl radicals in nonaqueous media

摘要: New complexes of diaza- and tetraaza-containing crown ethers, viz., 1,10-diaza-18-crown-6 (1), 1,4,8,12-tetraazacyclopentadecane (2), 1,4,8,11-tetraazacyclotetradecane (3), 1,4,8,11-tetrachloride tetraacetic acid tetrahydrate (4), with the divalent copper nickel ions Cl–, Br–, ClO4 –, NO3 –, AcO– counterions were synthesized. The exchange interactions these compounds paramagnetic salts TEMPO radical in MeOH—CHCl3 binary mixtures different compositions studied. plots linewidths hyperfine coupling components vs. concentration temperature show that frequency diffusion collisions is rate-limiting step for spin (strong regime). A strong dependence rate constant (k ex) on ether counterion structure was found. isotropic constants (a Cu) g factors (g i ) measured CuII ethers. In case 1—3 CuCl2, a Cu decreases linearly an increase Δg = g – 2.0023 series 3 < 2 1, whereas k ex increases same a decrease contact HFC nucleus (K) covalence bonding. For axial ligands (counterions), Cl– ClO4 – ≤ Br–; NO3 –. NiCl2, 1 4 ≈ 2. NiII NO3 – anions, values are almost independent anion nature. correlation electron-spin parameters discussed.