Change in the magnetic properties of [FeII(phen)3](PF6)2 in the solid state by combining grinding and annealing

By grinding crystalline [Fe-II(phen)(3)](PF6)(2), the effective magnetic moment, or chi(M)T, increased with simultaneous amorphization. Subsequent annealing further increased chi(M)T, despite the restoration of the crystallinity. This was explained by the recovery of the counterion, PF6-, from its strained state in the intact crystal to a less strained state towards higher spherical symmetry. The effects of annealing preceded by grinding suggest a novel method to control the magnetic states of coordination compounds without regard to their crystalline states.