Crystal structure of cis-7,8-dihydroxy-5,10,15,20-tetraphenylchlorin and its zinc(II)–ethylenediamine complex

Abstract

The title chlorin, 2PhH2, hydrogen-bonded to dimethylaminopyridine (DMAP), C44H32N4O2·C7H10N2, and its corresponding zinc(II) complex, 2PhZn, axially coordinated to ethylenediamine (EDA), [Zn(C44H30N4O2)]·C2H8N2, were isolated and crystallized by adventitious reduction of the corresponding osmate esters by DMAP and EDA, respectively. Known since 1996 and, inter alia, used for the preparation of a wide range of (planar and non-planar) chlorin analogues (so-called pyrrole-modified porphyrins), their conformational analyses in the solid state are important benchmarks. Both macrocycles are only modestly distorted from planarity and both are slightly more non-planar than the corresponding dimethoxy-derivative, but less planar than a free-base meso-pentafluorophenyl-based osmate ester. NSD analyses provide quantitative and qualitative analyses of the distortion modes. One origin of the non-planarity is presumably the avoidance of the eclipsed configuration of the two vic–cis diols on the pyrroline moiety; the resulting deformation of the pyrroline translates in some cases into the macrocycle. The structure of 2PhH2 features voids making up ca 26% of the unit-cell volume filled with highly disordered solvate molecules (chloroform and hexanes). 2PhZn crystallized with a 13.6 (4)% occupied solvate methanol molecule.

Keywords

• crystal structure
• porphyrinoids
• hydroporphyrins
• meso-phenylchlorins
• β-hydroxychlorin