Stable organic biradicals

In 1987 Ovchinnikov et al. announced the discovery of the first ferromagnetic organic polymer based on polydiacetylene chain with dangling nitroxyl radicals [8,9]. The compound was obtained by bulk polymerization of stable paramagnetic biradical BlPO initiated by light. The chemical structure of this compound is shown below. 

We would like to stress that in all these publications the authors investigated peculiarities of the rotational and translational diffusion of spin-probe molecules in various room temperature ionic liquids, comp)ared them with molecular dynamics in common organic solvents. Correlations with Stokes-Debye-Einstein or Stokes-Enstein laws were foimd. Areas in RTILs (polar, non-polar), in which spin probes (hydropElic, charged, hydrophobic) are localized were determined. Just recently, attention of the scientists was attracted to another type of molecular motions in the ionic liquids (Tran et al., 2007a, 2009). Such processes as well as solvent effects on them can be examined in detail by EPR sp>ectroscopy with the use of stable nitroxide biradicals (Parmon et al., 1977a, 1980). 

The C-H insertion reaction of phosphanylidene carbenoid is also found as a typical carbenoid reaction. The copper-mediated oxidative coupling reactions are powerful synthetic tools to construct some conjugated systems with the P=C skeleton, which are operated by treatment of oxygen. Lithium phosphanylidene carbenoids are applicable to synthesize the heavier heteroallenic compounds and stable biradical compounds. Moreover, an intriguing trimerization of phosphanylidene carbenoids is used to give the triphosphafulvene as an isomer of triphosphabenzene, which will lead to a novel organic chemistry. Indeed, the mentioned low-coordinated phosphorus compounds may well be applied to the synthesis of novel materials [5,64,65]. 

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