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Structural Determination of an Unusual Cu I ‐Porphyrin‐π‐Bond in a Hetero‐Pacman Cu‐Zn‐Complex
Author(s) -
Marquardt Michael,
Cula Beatrice,
Budhija Vishal,
Dallmann André,
Schwalbe Matthias
Publication year - 2021
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202004945
Subject(s) - porphyrin , xanthene , intramolecular force , copper , reactivity (psychology) , chemistry , moiety , metal , crystallography , zinc , photochemistry , stereochemistry , polymer chemistry , organic chemistry , medicine , alternative medicine , pathology
Abstract The synthesis and characterization of a hetero‐dinuclear compound is presented, in which a copper(I) trishistidine type coordination unit is positioned directly above a zinc porphyrin unit. The close distance between the two coordination fragments is secured by a rigid xanthene backbone, and a unique (intramolecular) copper porphyrin‐π‐bond was determined for the first time in the molecular structure. This structural motif was further analyzed by temperature‐dependent NMR studies: In solution at room temperature the coordinative bond fluctuates, while it can be frozen at low temperatures. Preliminary reactivity studies revealed a reduced reactivity of the copper(I) moiety towards dioxygen. The results adumbrate why nature is avoiding metal porphyrin‐π‐bonds by fixing reactive metal centers in a predetermined distance to each other within multimetallic enzymatic reaction centers.