EPR of BEDT-TTF salts with the magnetic cluster[PMo12O40]4− and the non magnetic [SiW12O40]4−

We present an EPR and SQUID study of the organic conductors, (BEDT-TTF)nX.solvent, where n=6 or 8, X=PMo12O40: n=8, X=SiMo12O40. The n=6 PMo12O40 salt shows two EPR signals (the conduction electrons and those localised on the clusters) while the n=8 salts a single EPR line averaged between the free electron g-value and that of the cluster for the Mo and only one signal from the BEDT-TTF radical for the non-magnetic SiW12O40 salt. The total magnetic susceptibilities are the sum of the individual contributions.