Magnetic and Structural Transitions at Dimerization of C<sub>60</sub><sup>•−</sup> in Ionic Fullerene Complexes with Metalloporphyrins: {(TMP<sup>+</sup>)<sub>2</sub>·M<sup>II</sup>TPP}·(C<sub>60</sub><sup>−</sup>)<sub>2</sub>·(C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub>)<sub>2</sub>·(C<sub>6</sub>H<s
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Ionic complexes containing C60•− radical anions and metalloporphyrins coordinatively bound to N,N′,N′-trimethylpiperazinium cations {(TMP+)2·MIITPP}·(C60−)2·(C6H4Cl2)2·(C6H5CN)2 [M = Zn (1) and Mn (2)] have been obtained. The crystal structures of 1 and 2 solved at 250 and 270 K, respectively, show layered packing in which fullerene layers alternate with the (TMP+)2·MIITPP ones. Fullerenes form pairs in the layer with short center-to-center distances of 10.044 and 10.077 Å, respectively. The structures of 1 and 2 solved at 100 K indicate the formation of singly bonded (C60−)2 dimers. That results in the transition of 1 from the paramagnetic to diamagnetic state accompanied by the disappearance of the electron paramagnetic resonance (EPR) signal of C60•− at 220−150 K. Dimerization in 2 results in a decrease in the magnetic moment from 6.36 to 6.00 μB at 200−150 K and a change in the shape of EPR signal. The room-temperature EPR signal shows a major broad component at g = 2.0678 (ΔH = 111.6 mT) attributed to both paramagnetic C60•− and high-spin (TMP+)2·MnIITPP species having strong exchange interaction. After dimerization, the signal is characteristic of isolated high-spin MnIITPP (g⊥ = 6 with |A| = 7.3 mT and g|| ≈ 2). Two TMP+ cations can coordinate to MII in (TMP+)2·MIITPP. However, a weak coordination bond is formed only with one cation with the MII···N(TMP+) distances of 2.489(2)−2.688(3) Å. As a result, metal atoms displace by ±0.232(3) Å (1, 250 K), ±0.231(1) Å (1, 100 K) and ±0.4684(7) Å (2, 270 K) out of the porphyrin plane to be located above and below the porphyrin plane with equal occupancies for both positions. The symmetry of the crystal structure of 2 decreases from monoclinic to triclinic under cooling. That results in unequal 0.85/0.15 occupation of the MnII positions at 100 K with displacement of the metal by 0.391(2) and 0.554(4) Å, respectively.
