Design of Molecular and Ionic Complexes of Fullerene C₆₀ with Metal(II) Octaethylporphyrins, M^IIOEP (M = Zn, Co, Fe, and Mn) Containing Coordination M−N(ligand) and M−C(C₆₀⁻) Bonds

The formation of coordination bonds between metalloporphyrins and N-containing ligands or C60•− was used to prepare molecular and ionic complexes of C60 with metal(II) octaethylporphyrins: {MIIOEP·DABCO}·C60·(Solvent) (M = Zn (4) and Co (5)); {(MDABCO+)·MIIOEP}·(C60•−)·(Solvent) (M = Zn (6), Fe (8), and Mn (9)), (MQ+)·{CoIIOEP·(C60−)}·C6H4Cl2 (10) and {(DMETEP+)·ZnIIOEP}·(C60•−)·(C60)0.5·C6H4Cl2 (12). New molecular complexes of C60 with ligand free metalloporphyrins MIIOEP·C60·(Solvent)1.5 (M = Zn (1), Co (2), and Fe (3)) were also obtained for comparison. Complexes 1−3 contain alternating pairs of C60 and MIIOEP molecules, whereas isostructural complexes 4−10 contain porphyrin channels accommodating zigzag fullerene chains. Complex 12 is a first example of fullerene complex containing simultaneously charged and neutral fullerene species arranged in zigzag chains and cavities formed by two (DMETEP+)·ZnOEP units. The coordination of DABCO, MDABCO+, DMETEP+, C60, and C60•− to MIIOEP was studied and their coordination abilities were compared. C60 weakly coordinates to FeIIOEP and CoIIOEP porphyrins with rather short M···C(C60) distances of 2.622 Å (3) and 2.685 Å (2). Only one N-containing ligand (L or L+) coordinates to MIIOEP in 4−9 and 12 to form five-coordinated L(L+)·MIIOEP species with the M···N(L or L+) bond lengths of 2.18−2.39 Å. These bonds are shorter by 0.049−0.055 Å for DABCO than for the MDABCO+ cation, and by 0.214 Å than for the DMETEP+ cation. Fullerenes are located from the opposite side of the porphyrin macrocycle relative to L (L+). They are essentially weaker ligands than L (L+) and form M···C(C60 or C60•−) distances longer than 2.84 Å. Neutral complex 3 with FeIIOEP in intermediate (S = 1) spin state manifests a Weiss temperature of 2.6 K. C60•− coexists with diamagnetic ZnIIOEP in 6 and high-spin FeIIOEP and MnIIOEP in 8 and 9. The Weiss temperatures of −17.8, −42.0, and −2.5 K, respectively, indicate antiferromagnetic coupling of spins in these complexes. The MQ+ cation is not coordinated to CoIIOEP in 10 providing the formation of stable Co−C(C60−) coordination bonds of 2.266(3) Å length and diamagnetism of the complex.