MAGNETIC-PROPERTIES OF METAL-QUINONE HIGH-SPIN COMPLEXES PREPARED BY SOLID-STATE MECHANO-ACTIVATION AND BY CHEMICAL SYNTHESIS IN SOLUTION -COMPARATIVE-STUDY WITH VERY HIGH-FIELD AND LOW-TEMPERATURE EPR AND ENDOR

EPR spectroscopy at high frequencies and low temperatures and ENDOR sp ectroscopy at X- and W-bands have been applied to investigate two- and three-spin complexes of the type MQ(2)(.) and MQ(3)(.) generated by m echanochemical treatment (by grinding or by the action of elastic wave s) of solid mixtures of quinones and metals (M = Al, Ga, In, Cd, Sn, Z n). In addition, complexes obtained in liquid-phase reactions of metal amalgams with quinones were investigated. The magnetic-resonance para meters and the observed thermal spin polarization provide evidence for the identity of the magnetic complexes produced in solutions and by s olid-state mechanochemical treatment. In particular, the presence of g round-state triplet and quartet species has been demonstrated in both cases. In addition, the exchange and the dipole-dipole interaction par ameters were evaluated, their comparison providing information about t he electronic intramolecular interaction.