Exchange couplings in the free radical nitroxide tanol suberate determined by static magnetic methods and room temperature proton relaxation

Magnetic properties of the free radical nitroxide tanol suberate may be interpreted in terms of a quasi-unidimensional Heisenberg system. Temperature dependent static methods and frequency dependent room temperature proton relaxation are applied to the determination of exchange couplings. The intrachain exchange coupling J is positive and is about 1.1 K. Two other exchange couplings have to be considered : near neighbouring chains, connected by an interchain coupling J'1 positive of about 0.09 K form sheets. These sheets are connected together by a coupling J'2 negative of about 0.03 K.