Design of Molecular and Ionic Complexes of Fullerene C60 with Metal(II) Octaethylporphyrins, MIIOEP (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 C-60(center dot-) was used to prepare molecular and ionic complexes of C-60 with metal(II) octaethylporphyrins: {(MOEP)-O-II center dot DABCO} C-60 center dot(Solvent) (M = Zn (4) and Co (5)); {(MDABCO(+)) center dot (MOEP)-O-II} center dot (C-60(center dot-)) center dot(Solvent) (M = Zn (6), Fe (8), and Mn (9)), (MQ(+))center dot{(CoOEP)-O-II center dot(C-60(-))}center dot C6H4Cl2 (10) and {(DMETEP+) center dot (ZnOEP)-O-II} center dot (C-60(center dot-)) center dot (C-60)(0.5)center dot C6H4Cl2 (12). New molecular complexes of C-60 with ligand free metalloporphyrins (MOEP)-O-II center dot C-60 center dot(Solvent)(1.5) (M = Zn (1), Co (2), and Fe (3)) were also obtained for comparison. Complexes 1-3 contain alternating pairs of C-60 and (MOEP)-O-II 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+)center dot ZnOEP units. The coordination of DABCO, MDABCO(+), DMETEP+, C-60, and C-60(center dot-) to (MOEP)-O-II was studied and their coordination abilities were compared. C-60 weakly coordinates to (FeOEP)-O-II and (CoOEP)-O-II porphyrins with rather short M center dot center dot center dot C(C-60) distances of 2.622 angstrom (3) and 2.685 angstrom (2). Only one N-containing ligand (L or L+) coordinates to (MOEP)-O-II in 4-9 and 12 to form five-coordinated L(L+)center dot(MOEP)-O-II species with the M center dot center dot center dot N(L or L+) bond lengths of 2.18-2.39 angstrom. These bonds are shorter by 0.049-0.055 angstrom for DABCO than for the MDABCO(+) cation, and by 0.214 angstrom 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 center dot center dot center dot C(C-60 or C-60(center dot-)) distances longer than 2.84 angstrom. Neutral complex 3 with (FeOEP)-O-II in intermediate (S = 1) spin state manifests a Weiss temperature of 2.6 K. C-60(center dot-) coexists with diamagnetic (ZnOEP)-O-II in 6 and high-spin (FeOEP)-O-II and (MnOEP)-O-II 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 (CoOEP)-O-II in 10 providing the formation of stable Co-C(C-60(-)) coordination bonds of 2.266(3) angstrom length and diamagnetism of the complex.