The crystal structures of the 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane, TCNQF(4), electron transfer salts of meso-tetraphenylporphinatomagnesium(II), [MgTPP][TCNQF(4)].PhMe and [MgTPP][TCNQF(4)].3(1,2-C6H4Cl2), and meso-tetrakis(3,4,5-trimethoxyphenyl)porphinatomagnesium(II), [MgT(3,4,5-OMe)PP][TCNQF(4)].3(1,2-C6H4Cl2), provide the first structurally characterized examples of 1-D metal-radical chains involving [Mg-II(porphyrin(.))](+). These salts possess [TCNQF(4)](.-) stabilized by trans-mu-coordination to Mg(II) and exhibit nu(CN) at 2199 and 2177, 2212 and 2187, and 2194 and 2172 cm(-1), respectively. The [TCNQF(4)](.-) species is planar and bridges two cations with MgN distances of 2.266(16), 2.221(2), and 2.276(3) Angstrom, respectively, which are shorter than the MnN 2.321(3) Angstrom distance observed for [MnT(3,4,5-OMe)PP][TCNQF(4)].3(1,2-C6H4Cl2). The room-temperature effective moments for [MgTPP]-[TCNQF(4)].xS (S = PhMe and 1,2-C6H4Cl2) and [MgTPP][C-4(CN)(6)].PhMe are consistent with the calculated spin only value of 2.45 mu(B) with weak antiferromagnetic coupling (J(intra)/k(B) similar to -2.9 K; H = -2JS(a).S-b) for these [TCNQF(4)](.-) salts and for this [C-4(CN)(6)](.-) salt (J(intra)/k(B) similar to -0.8 K) on the basis of fits to several models. The coupling is significantly reduced with respect to that of the Mn analogues due to lack of spin on the metal site for [Mg-II(por(.))](+). The antiferromagnetic coupling is enhanced for [MgT(3,4,5-OMe)PP][TCNQF(4)] with respect to [MgTPP][TCNQF(4)] as [TCNQF(4)](.-) gets closer to the [Mg-II(por(.))](+) plane, which leads to greater interactions and coupling.