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Impact of Distortion of Porphyrins on Axial Coordination in (Porphyrinato)zinc(II) Complexes with Aminopyridines as Axial Ligands
Author(s) -
Kojima Takahiko,
Nakanishi Tatsuaki,
Honda Tatsuhiko,
Harada Ryosuke,
Shiro Motoo,
Fukuzumi Shunichi
Publication year - 2009
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200801040
Subject(s) - chemistry , aminopyridines , pyridine , zinc , intermolecular force , crystallography , stereochemistry , porphyrin , molecule , pyrrole , 2 aminopyridine , non covalent interactions , isoindole , medicinal chemistry , photochemistry , organic chemistry , hydrogen bond
A series of (porphyrinato)zinc(II) compounds were synthesized with use of 5,10,15,20‐tetraphenylporphyrin (H 2 TPP), 2,3,5,10,12,13,15,20‐octaphenylporphyrin (H 2 OPP), and 2,3,5,7,8,10,12,13,15,17,18,20‐dodecaphenylporphyrin (H 2 DPP). Those compounds form complexes with aniline, pyridine, and 3‐ and 4‐aminopyridines as axial ligands. X‐ray crystallography was performed on the complexes with 3‐aminopyridine (3‐AP) and 4‐aminopyridine (4‐AP) as axial ligands. 3‐Aminopyridine was revealed to bind through the amino group to the Zn(OPP), exhibiting intermolecular π–π interaction between 3‐AP and one of the pyrrole rings and intermolecular NH–π interactions of the coordinated amino group with two β‐phenyl groups of an adjacent molecule. In solution, the aminopyridines form a single species at ambient temperature and are assumed to have pyridine coordination through the aromatic pyridine nitrogen atom. Variable‐temperature NMR spectroscopy in CD 2 Cl 2 indicates that two different species exist at lower temperatures, suggesting that amino‐bound complexes of 3‐AP can be formed as a metastable species in solution, which is stabilized in the crystal as a result of noncovalent interactions. The binding constants of aminopyridines to the three kinds of (porphyrinato)zinc complexes reveal enhancement of the axial ligation by virtue of the distortion of the porphyrin ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)