Structure and Magnetic Properties of Ferrimagnetic Mn(III)tetrakis(4-methoxy-tetrafluorophenyl)porphyrin tetracyanoethanide, [MnTF₄OMePP][TCNE]^.2PhMe, D. K. Rittenberg, K-i. Sugiura, Y. Sakata, I. A. Guzei, A. L. Rheingold, J. S. Miller, Eur. J. Chem. 5, 1874-1881 (1999).

The reduction of meso-tetrakis(pentafluorophenyl)porphinatomanganese(III) chloride, Mn^IIITF₅PPCl, with methanolic sodium borohydride and subsequent reaction with tetracyanoethylene, TCNE, leads to formation of the magnet meso-tetrakis[2,3,5,6-tetrafluoro-4-methoxyphenyl]porphinatoman ganese(III) tetracycanoethanide, [Mn^IIITF₄OMePP]⁺[TCNE]^{•-.2PhMe, which has been characterized by single crystal X-ray diffraction, magnetic, and thermal measurements. The structure undergoes a reversible phase transition below –100 oC (173 K) and the structure was solved and refined in a monoclinic unit cell both at –45 oC (228 K) [P21/n, a = 9.3926 (2) Å, b = 25.3254 (4) Å, c = 13.2053 (2) Å,} b = 97.203 (2)û, V = 3116.37 (10) Å₃, Dcalcd = 1.478 g cm^-3, Z = 2, 4019 reflections, R₁(Fo) = 7.43% for the data with F > 2s(F) and 8.71% for all data], and –179 ^oC (94 K) [P21/a, a = 14.8410 (5) Å, b = 25.366 (1) Å, c = 16.7333 (5) Å, b = 108.091 (2)û, V = 5987.91 Å3, Dcalcd = 1.540 g cm-3, Z = 4, 11,792 reflections, R(F_o) = 6.9% for the data with F > 3s(F)]. [Mn^IIITF₄OMePP][TCNE]^.2PhMe has a linear chain (1-D) coordination polymer motif comprised of alternating [Mn^IIITF₄OMePP]⁺ cations and bridging [TCNE]^•-. At –45 ^oC the 1-D chain is uniform with a MnNTCNE distance of 2.320 (4) Å, while at –179 ^oC the 1-D chain is nonuniform with MnNTCNE distances of 2.291 (2) and 2.283 (2) Å and the [TCNE]^•- is disordered over two orientations in a 79:21 ratio. This slight chain nonuniformity is observed for the first time for a magnetically ordered system. The observed crystallographic phase change that occurs between -100 and -162 ^oC was not observed via the magnetic or thermal studies. Hence, structures should be determined at the lowest possible temperature, to enhance confidence that a reliable structure-property relationship can be obtained. The temperature dependence of the magnetic susceptibility above 200 K can be fit to a Curie-Weiss expression with an effective q (q') value of 93 K. Intrachain coupling was modeled to a Seiden expression (H = -2Sa•Sb) with a Jintra of -235 K (-163 cm^-1; 326 cal/mol; 29 meV), and 10 Hz ac magnetic susceptibility indicate an ordering temperature, T_c, of 10.3 K. The frequency dependence of the ac susceptibility indicates spin glass behavior.