Formation of Antiferromagnetically Coupled C₆₀^•- and Diamagnetic (C₇₀^-)₂ Dimers in Ionic Complexes of Fullerenes with (MDABCO⁺)₂·M^IITPP (M = Zn, Co, Mn, and Fe) Assemblies

A series of ionic multicomponent complexes comprising C60 and C70 anions and coordinating assemblies of methyldiazabicyclooctane cations with metal tetraphenylporphyrins, (MDABCO+)2·MIITPP·(C60(70)-)2·Sol. (C60, M = Zn (1); C60, M = Co (2); C60, M = Mn (3); C60, M = Fe (4); C70, M = Mn (5); and C70, M = Fe (6)) has been obtained. IR− and UV−vis-NIR spectra of 1−6 justified the formation of C60•- in 1−4 and single-bonded (C70-)2 dimers in 5 and 6. Co and Mn atoms are six-coordinated in the (MDABCO+)2·MIITPP units with relatively long M−N bonds of 2.475(2), 2.553(2), and 2.511(3) Å for 2, 3, and 5, respectively. Isostructural complexes 2 and 3 contain C60•- zigzag chains separated by the (MDABCO+)2·MIITPP units, whereas in 5 the layers formed by the (C70-)2 dimers alternate with those composed of the (MDABCO+)2·MnIITPP units and noncoordinating MDABCO+ cations. Negative Weiss constants of −13 (1), −2 (3), and −2 (4) K indicate the antiferromagnetic interaction of spins, which decreases the magnetic moment of the complexes below 70−120 K. The EPR signals of 1 and 4 attributed to C60•- are split into two components at the same temperatures, which broaden and shift to higher and lower magnetic fields with the temperature decrease. Complexes 2 and 3 show single EPR signals with g-factors equal to 2.1082 and ∼2.4 at 293 K, respectively. These values are mean between those characteristic of MIITPP and C60•-, and, consequently, the signals appear due to exchange coupling between these paramagnetic species. The antiferromagnetic ordering of C60•- spins below 70−100 K shifts g-factor values closer to those characteristic of individual MIITPP (g = 2.1907 (2) and ∼4.9 (3) at 4 K). In contrast to 1−4, complex 5 shows paramagnetic behavior with Weiss constant close to 0.