Structure and Magnetic Properties of meso-tetrakis(3,4,5-trimethoxyphenyl)-porphyrinatomanganese(III ) 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-p-quinodi-methenide. The First Example of an Isolated [TCNQF4].-, M. T. Johnson, A. M. Arif, J. S. Miller, Eur. J. Inorg. Chem. 39, 0000-0000 (2000).

The crystal structure of meso-tetrakis(3,4,5-trimethoxyphenyl)porphinato-manganese(III) 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethenide, [MnT(MeO)₃PP]^-[TCNQF₄]•3(o-C₆H₄Cl₂), 1•3C₆H₄Cl₂, provides the first example of a nondimeric [TCNQF₄]^•- that is stabilized by trans-m- coordination to Mn(III). 1•3C₆H₄Cl₂ crystallized in the monoclinic C₂/c space group [a = 16.9486(10)Å, b = 25.7170(14)Å, c = 19.4009(12)Å, b = 107.091(4)û, V = 8082.8(8) Å3, T = 200 K, Z = 4, R(Fû) = 0.0547]. [TCNQF₄]^•- was confirmed from the crystal structure data, as well as the infrared n_CN at 2196 and 2165 cm^-1. The [TCNQF₄]^•- is planar with the methylene carbon-ring carbon distance of 1.41 Å, which is 0.038 Å longer than that for TCNQF₄. 1•3C₆H₄Cl₂ forms 1-D zigzag chains of alternating 1⁺ and [TCNQF₄]^•-, where the Mn(III) are bound in a trans-m- fashion with Mn-N and intrachain Mn^...Mn distances of 2.321(3) Å and 12.685 (4) Å, respectively. The MnNC angle and the dihedral angle between the [TCNQF₄]^•- and the mean MnN₄ planes are 135.9(2)° and 46.4° respectively, with the phenyl rings rotated 80° with respect to the mean porphyrin plane. The magnetic susceptibility of 1•2.3C₆H₄Cl₂ can be by the Curie-Weiss expression with q = -37 K (T > 250 K) and q' = +29 K (75 < T < 200 K) with an observed minimum in cT(T), typical of ferrimagnets, at 215 ± 10 K. At 2 T the magnetization is 14,900 emuOe/mol or 89% of 16,755 emuOe/mol expected for S_Tot = 2 - 1/2 = 3/2 system. The intrachain antiferromagnetic coupling, J/kB, is -71 K (-49 cm^-1; -61 meV) basedon a fit to the Seiden expression for noninteracting chains comprised of alternating quantum (S = 1/2) and classical (S > 1/2) spins and the Hamiltonian H = -2JS_a•S_b. 1•2.3C₆H₄Cl₂ ferrimagnetically orders at 7.3 K (based on the maxima in the 10 Hz c'(T) data). Hysteresis is observed at 2 K with coercive field, H_cr, of 17.1 kOe and remanent magnetization of 7,200 emuOe/mol; hysteresis is not observed at 5 K. 1•2.3C₆H₄Cl₂ also displays metamagnetic behavior at 2 K above a critical field of 20.2 kOe. The frequency dependent transitions observed in the c'(T) and c"(T) a.c. data are attributed to the transition to a spin glass or superparamagnetic state.