Ionic and Neutral C₆₀ Complexes with Coordination Assemblies of Metal Tetraphenylporphyrins, M^IITPP₂·DMP (M = Mn, Zn). Coexistence of (C₆₀^-)₂ Dimers Bonded by One and Two Single Bonds in the Same Compound

Coordination assemblies of metal tetraphenylporphyrins, MIITPP2·DMP (M = Mn, Zn) were shown to form ionic multicomponent and neutral complexes with fullerene, {(MnIITPP)2·DMP}·(C60-)2·(DMETEP+)2·(C6H4Cl2)5 (1) and {(ZnTPP)2·DMP}·(C60)2·(C6H5Cl)4 (2), where DMP = N,N‘-dimethylpiperazine and DMETEP+ = the cation of N,N‘-dimethyl-N‘-ethylthioethylpiperazine. The crystal structure of 1 contains zigzag chains of the (C60-)2 dimers alternating with the DMETEP+ cations in the channels formed by the (MnIITPP)2·DMP units, whereas in 2 zigzag chains of the C60 molecules are separated by the (ZnTPP)2·DMP units and C6H5Cl molecules. The (MIITPP)2·DMP assemblies (M = Mn, Zn) have axial M−N(DMP) bonds of 2.315(2) and 2.250(2) Å length, average equatorial M−N(DMP) bonds elongated to 2.141(3) and 2.077(2) Å, and MII atoms displaced from the porphyrin plane toward the ligand by 0.677 and 0.485 Å, respectively. The single-bonded σ-(C60-)2 dimer coexists in 1 with the (C60-)2 dimer bonded by two single bonds with 86/14 occupancy factors. The σ-(C60-)2 dimers are unusually stable and begin to dissociate only above a temperature of 320−330 K that results in the increase of the magnetic moment of 1 from 8.33 μB (320 K) to 8.66 μB (360 K). The electron paramagnetic resonance (EPR) signal of the dimeric phase (T < 320 K) with the features spread over the range of 0−0.7 T was attributed to the interacting Mn2+ centers in the (MnIITPP)2·DMP units. The dissociation of the σ-(C60-)2 dimers to the EPR-active C60•- radical anions manifests a new broad Lorenz signal above 320 K with g = 2.0179 and ΔH = 65.5 mT. This signal can appear due to the exchange coupling between paramagnetic (MnIITPP)2·DMP and C60•- species. The vis−NIR spectrum of the σ-(C60-)2 dimers is discussed.