Series of radical salts derived from a 2,4,6-triphenylpyridinium (TPP) carrying TEMPO-substituent and transition metal complexes were prepared by the anion exchange of the TPP-TEMPO tetrafluoroborate with [n-Bu(4)N][Ni(dmit)(2)], [n-Bu(4)N](2)[Pd(dmit)(2)], [n-Bu(4)N(2)][Pt(dmit)(2)], [n-Bu(4)N][Ni(mnt)(2)], or [n-Bu(4)N](2)[Ni(mnt)(2)] to give crystals with different structural features. While weak antiferromagnetic interactions of the Curie-Weiss behavior of S = 1/2 spin are predominantly observed in the salts of Pd(dmit)(2), Pt(dmit)(2) and Ni(mnt)(2), the magnetic behavior of 1:1 Ni(dmit)(2) salt can be explained by the additional contribution from the spins on Ni(dmit)(2) anions (chi - chi(TEMPO)), obeying the 2D Heisenberg model. A couple of the oxidized salts, [TPP][Ni(dmit)(2)] as well as [TPP](2)[Pd(dmit)(2)], exhibit semi-conducting properties with relatively high room temperature conductivities. (C) 2009 Elsevier B.V. All rights reserved.