STRUCTURE AND MAGNETIC-PROPERTIES OF ANTIFERROMAGNETIC MANGANESE(III)TETRAKIS(4-METHOXYPHENYL)PORPHYRIN TETRACYANOETHENIDE, [MNTOMEPP][TCNE]CENTER-DOT-2PHME, AND MANGANESE(III) TETRAKIS(2-FLUOROPHENYL)PORPHYRIN TETRACYANOETHENIDE, [MNTFPP][TCNE]CENTER-DOT-2PHME

The tetracyanoethylene (TCNE) electron-transfer salts of meso-tetrakis (4-methoxyphenyl)- and so-tetrakis(2-fluorophenyl)porphinatomanganese( II) (II), [MnTOMePP][TCNE] . 2PhMe, 1, and [MnTFPP][TCNE] . 2PhMe, 2, respectively, have een structurally and magnetically characterized. 1 and 2 belong to the triclinic Pi (No. 2) space group [1, a = 9.896(2) Angstrom, b = 10.256(3) Angstrom, c = 14.447(2) Angstrom, alpha = 82.6 4(2)degrees, beta = 92.40(1)degrees, gamma = 109.07(2)degrees, T = -80 degrees C, Z = 1, and R(F-0) = 0.0295; 2, a = 10.185(5) Angstrom, b = 11.081(3) Angstrom, c = 12.378(3) Angstrom, alpha = 107.55(2)degrees, beta = 82.88(3)degrees, gamma = 111.09(3)degrees, T = -80 degrees C, Z = 1, and R(F-0) = 0.0421]. 1 and 2 are coordination polymers with th e Mn(III) sites bridged by trans-mu-sigma-[TCNE](.-). The [TCNE](.-) i s orientationally disordered in 2, with the minor form being rotated b y 90 degrees with respect to the major form and in the same plane as t he major form in an approximate 5:1 ratio. The Mn-N and intrachain Mn Mn distances are 2.289 and 2.313 Angstrom and 10.256 and 10.185 Angstr om. and the Mn-N-C and the dihedral angle between the mean MnN4-porphy rin and the mean [TCNE](.-) planes are 165.53 and 78.1 degrees and 148 .6 and 55.4 degrees for 1 and the occupancy-weighted average of 2, res pectively. For 1 above 250 K the susceptibility can be fit by the Curi e-Weiss expression with theta = -65 K, while between 75 and 190 K an e ffective theta of +21 K is observed; for 2 above 225 K, theta is -71 K , while between 40 and 100 K the effective theta is +45 K. The initial negative theta values along with minima in the T-chi(T) data at 134 K (X = OMe) and 240 K (X = F) are consistent with antiferromagnetic cou pling. One (chi)''(T) and two (chi)'(T) peaks are observed for both 1 and 2. The higher temperature [similar to-10 K (1) and 12.5 K (2)] (ch i)'(T) peaks are frequency independent, lack a corresponding (chi)''(T ) absorption, and are assigned to a transition to an antiferromagnetic state. In contrast, the lower-temperature frequency dependent [5.6 K (1) and 7.5 K (2) at 10 Hz] (chi)'(T) peaks have a corresponding frequ ency dependent (chi)''(T) peaks and are assigned to the transition to a spin-glass or superparamagnetic state. The T-c's are defined as (chi )'(T) data taken at 10 Hz and are listed above.