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Bis( μ ‐oxo)dimetal “Diamond” Cores in Copper and Iron Complexes Relevant to Biocatalysis
Author(s) -
Que, Jr. Lawrence,
Tolman William B.
Publication year - 2002
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/1521-3773(20020402)41:7<1114::aid-anie1114>3.0.co;2-6
Subject(s) - chemistry , isomerization , biocatalysis , extended x ray absorption fine structure , crystallography , covalent bond , copper , manganese , metal , stereochemistry , catalysis , reaction mechanism , absorption spectroscopy , organic chemistry , physics , quantum mechanics
Although quite a familiar feature in high‐valent manganese chemistry, the M 2 ( μ ‐O) 2 diamond core motif has only recently been found in synthetic complexes for M=Cu or Fe. Structural and spectroscopic characterization of these more reactive Cu 2 ( μ ‐O) 2 and Fe 2 ( μ ‐O) 2 compounds has been possible through use of appropriately designed supporting ligands, low‐temperature handling methods, and techniques such as electrospray ionization mass spectrometry and X‐ray crystallography with area detector instrumentation for rapid data collection. Despite differences in electronic structures that have been revealed through experimental and theoretical studies, Cu 2 ( μ ‐O) 2 and Fe 2 ( μ ‐O) 2 cores exhibit analogously covalent metal–oxo bonding, remarkably congruent Raman and extended X‐ray absorption fine structure (EXAFS) signatures, and similar tendencies to abstract hydrogen atoms from substrates. Core isomerization is another common reaction attribute, although different pathways are traversed; for Fe, bridge‐to‐terminal oxo migration has been discovered, while for Cu, reversible formation of an O−O bond to yield a peroxo isomer has been identified. Our understanding of biocatalysis has been enhanced significantly through the isolation and comprehensive characterization of the Cu 2 ( μ ‐O) 2 and Fe 2 ( μ ‐O) 2 complexes. In particular, it has led to the development of new mechanistic notions about how non‐heme multimetal enzymes, such as methane monooxygenases, fatty acid desaturase, and tyrosinase, may function in the activation of dioxygen to catalyze a diverse array of organic transformations.