Porphyrin-fullerene, C_(60), cocrystallates: Influence of C _(60) on the porphyrin ring conformation

摘要

To examine the influence of fullerene on the macrocyclic ring conformation, crystal structures of a series of cocrystals of 2,3,5,10,12,13,15,20- octaphenylporphyrin, M(TPP)(Ph)_4 (M = 2H, Co(II), Cu(II)), and 2,312,13-tetramethyl-5,7,8,10,15,17,18,20-octaphenyl-porphinato copper(II), CuTPP(Ph)_4(CH_3)_4, derivatives with fullerene, C_(60), were elucidated. Furthermore, crystal structures of the parent porphyrins, M(TPP)(Ph)_4 (M = Co(II), Cu(II)) complexes, were also determined. All the cocrystals revealed one-to-one stoichiometry between the porphyrin and C_(60) and were free of lattice solvates. Porphyrin rings in M(TPP)(Ph)_4·C_(60) cocrystals revealed significant distortion with the root-mean-square (rms) value as high as 0.265(2) ? which is the average deviation of the 24 atoms core from the least-squares plane. Crystal structures of the parent M(TPP)(Ph)_4 (M = Co(II), Cu(II)) complexes indicated near planarity of the 24-atom core with the root-mean-square deviation value of 0.016(2) ?. Molecular packing in the M(TPP)(Ph)_4·C_(60) cocrystals showed essentially one-dimensional chains interconnected by weak interporphyrin and porphyrin-fullerene close contacts. The N_(porphyrin)?C(C _(60)) shortest distances between the H_2(TPP)(Ph)_4 (M = 2H, Co(II), Cu(II)) and fullerene in the cocrystals are 3.031(5) ?, 3.062(4) ?, and 3.059(3) ?, respectively. Similarly, close contact M?C distances in the M(TPP)(Ph)_4·C_(60) (M = Co(II), Cu(II)) are 2.761(6) ? and 2.886(3) ?, respectively. In the Cu(TPP)(Ph)_4(CH_3)_4·C_(60) cocrystal, the shift of macrocyclic ring toward planarity was evidenced from the rms value of 0.236(2) ? relative to that observed in CuTPP(Ph) _4(CH_3)_4·CHCl_3 (0.391(2) ?). The distortion of the macrocyclic ring in M(TPP)(Ph) _4·C_(60) complexes was examined by normal-coordinate-structure decomposition (NSD) analyses. Their out-of-plane displacement of the core atoms revealed predominant contribution being saddle (～95-96%) and gentle domed distortions (3-4%). In the case of M(TPP)(Ph)_4(CH_3)_4·C_(60) cocrystal, it showed mainly saddled (～83%), minimal ruffled (8%) and domed (8%) distortions of the macrocyclic ring. In-plane displacement on the 24-atom core of the porphyrin in these cocrystallates features generally a varying degree of N-str (B_(1g)) and bre (A_(1g)) distortions.