Screening of different interactions in oxo-manganese porphyrin dimers containing axial N-donor ligands: a theoretical study.

A theoretical analysis for describing the dimeric assemblies of high-valent manganese(v)-oxo meso -tetraphenylporphyrin (TPP) ([(TPP)Mn V O] 2 2+ ) and meso -tetrakis(pentafluorophenyl)porphyrin (TPFPP) ([(TPFPP)Mn V O] 2 2+ ) in the presence of axial N-donor ligands is presented. Our theoretical results revealed two types interactions in dimers: a sandwich-like interaction between phenyl rings of porphyrin molecules, and a non-bonded T-shape interaction between nitrogen donors attached to Mn centers. The curvature in the geometry of porphyrin in the [(TPP)Mn V O] 2 2+ /N-donor system is significantly smaller than that of [(TPFPP)Mn V O] 2 2+ /N-donor system. Moreover, the Mn-N (ax) distances in [(TPFPP)Mn V O] 2 2+ /N-donor system are shorter than those of [(TPP)Mn V O] 2 2+ /N-donor system. Also, the donor-acceptor interaction between the imidazoles and the Mn centers are stronger than those of the other ligands in both porphyrins. These results are supported by atoms in molecules (AIM) and natural bond orbital (NBO) analysis.