Magnetic Behavior of N-(Arylthio)-2, 4, 6-Triphenylanilino Radical Crystals

In order to find the conditions which prevent the dimerization among molecules in the crystal, we have searched long-range antiferromagnetic ordered purely organic systems, such as linear chain organic antiferromagnets. The dimerization is one of the most difficult problems be solved in order to obtain the organic ferrimagnets. This paper deals with the magnetic behavior of polycrystals of m-nitro, p-nitro, and 3, 5-dichloro-N-(arylthio)-2,4,6-triphenylanilino radicals. We have found that all of them exhibit long-range antiferromagnetic chain behaviors (at least larger than 7 spins). The temperature dependence of the magnetic susceptibility of the m-nitro radical crystal was well analyzed in terms of a Heisenberg infinite alternating-linear-chain model with J/k = -26 K and the alternating parameter α = 0.92. The temperature dependence of the ESR line-width was also consistent with the dataof the magnetic susceptibility. The other two compounds have shown similar magnetic behaviors with the larger J/k values. The mechanism of their large antiferromagnetic interaction and the condition for the long-range ordering have been discussed.