An increase in the intensity of the ESR signal and of its g value was
observed in the course of annealing of the diamagnetic product of the
reaction between magnesium amalgam and a toluene solution of C-60. The
formation of a crystalline substance MgxC60 with semiconductor proper
ties was assumed. The ESR spectra of the products of vapor-phase synth
esis of MgC60 and HgxC60 were recorded.