Imino nitroxide radicals

Nitronyl nitroxide radical Imino nitroxide radical 3,5- Bu-sonoquinonato... 

Figure 9.2 The radical structure of nitronyl nitroxide radical, imino nitroxide radical, and semo-quinonato.

Tsukuda, T, Suzuky, T., and Kaizaki, S. (2002) Synthesis, spectroscopic and magnetic properties of lan-thanide(lll) complexes with a chelated imino nitroxide radical. Journal of the Chemical Society, Dalton Transactions, 1721-1726. 

The imino nitroxide radicals (201) exhibit a similar spin distribution to that of the nitronyl nitroxide radicals. The methyl protons on the two sides of the imino nitroxide ring are found to have different coupling constants. This is thought to be due either to different relative geometries or to an interaction between the methyl protons on the... 

Upon irradiation with a Xe lamp (100 W), the typical five-line spectrum characteristic of the nitronyl nitroxide radical 114 (g= 2.0066) was progressively transformed into a seven-line spectrum characteristic of an imino nitroxide radical (Scheme 24). It was proposed that during the irradiation, selective deoxygenation of the radical 114 to the radical 115 had occurred <2003S2145>. 

Figure 4 shows that similar absorption spectra are observed for nitronyl nitroxide and imino nitroxide radicals, with the transitions for the imino nitroxides occurring higher in energy by approximately 4000 cm1. The average energy interval determined from bands a to d in the absorption spectra of the IMBzImH radical is 1450 cm-1, a value similar to the NITBzImH radical, shown as the dotted trace in Fig. 4. All band maxima for the imino nitroxide radical are included in Table 2.

A molecular compound the antibonding wave function in an imino nitroxide free radical... 

Figure 5. Nitroxide radicals and their SOMO (a) nitronyl nitroxide and (b) imino nitroxide.

Nitronyl and imino nitroxide free radicals are also among the most versatile spin carriers which are widely used in the design of molecular magnets. Their delocalised unpaired electrons make them convenient building blocks and ideal magnetic bridges between magnetic metals, to achieve new compounds with particular... 

Zheludev, A., Bonnet, Luneau, D. et al. (1995) The spin density in an imino nitroxide free radical a polarized-neutron study, Physica B, 213-214, 268-271. 

Diradical species 35a and 35b, in which two imino nitroxide 35a or nitronyl nitroxide 35b radical centers are attached to thieno[2,3-. ]thiophene, were prepared and their intramolecular exchange interactions were investigated in frozen solutions by means of electron spin resonance (ESR) spectroscopy and magnetic susceptibility measurements at cryogenic temperature <1996T6893>. 

Lescop, C., Luneau, D., Rey, R et al. (2002) Synthesis, structures, and magnetic and optical properties of a series of europium(lll) and gadolinium(lll) complexes with chelating nitronyl and imino nitroxide free radicals. Inorganic Chemistry, 41, 5566-5574. 

Fig-1 Schematic representations of the nitronyl nitroxide (NIT) and imino nitroxide (IM) radicals studied by optical spectroscopy. Ligator atoms for lanthanide complexes are denoted by asterisks. The stoichiometry of the metal complexes is given, with Rad and hfac denoting radical and hexafluoroacetylacetonato ligands, respectively... 

Diradical species 296-299, in which two nitronyl nitroxide (ONC = NO) or imino nitroxide (NCNO) radical centres are bound to the thieno[2,3-Z)]thiophene and thieno[2,3-Z)]thieno[3, 2 -d]thiophene chromophores, were investigated. Their intramolecular exchange coupling in frozen solutions and the magnetic sensitivity at low temperatures were examined by ESR spectroscopy (95TL5543, 96T6893). 

The ESR spectra of mononitronyl nitroxide and imino nitroxide free radicals bound to isomeric thieno[3,2-Zt]- (145) and -[2,3-Zt]thiophenes (142) were measured in toluene at room temperature (69TL239). 

Formation of Stable Radicals. The oxidation of A(,A( -di-hydroxyimidazolidines (7) with sodium periodate or silver(I) oxide affords several stable oligopyridine-based nitronyl-nitroxide biradicals (8) in moderate to good yields, under phase transfer conditions (dichloromethane-water medium) at 0 °C (eq 36). Also, the related bis-iV-hydroxyimidazolidines react in a similar way furnishing the corresponding imino-nitroxide biradicals albeit in modest yields. ... 

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