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Fig. 8 Reaction energy diagrams of O 2 activation on [Cu I 2 Cu II (μ-O)] 2+ -MOR in the corresponding
ground state. Energies are in kcal/mol. Reproduced with permission from Ref. [32]. Copyright 2018
American Chemical Society
Recently, Ikuno et al. systematically described that the O=O bond cleavage of O 2
forming the [Cu 3 (μ-O) 3 ]
2+ active site actually occurs at low temperature (50–200 °C),
but dehydration, auto-reduction, and subsequent migration of the Cu centers at high
temperature are required beforehand [36]. As shown in Fig. 9, at the initial stage,
two [Cu
II OH]
+ species derived from a dehydration of [Cu
II (H 2 O) n ]
2+ are condensed
Fig. 9 Elementary steps in the formation of [Cu 3 (μ-O) 3 ] 2+ active site in Cu-MOR: (1) Moderatetemperature dehydration and auto-reduction of the Cu centers, (2) high-temperature migration of
the reduced Cu centers to form a favorable precursor, and (3) low-temperature O 2 or N 2 O activation
forming the [Cu 3 (μ-O) 3 ] 2+ active site. Adapted with permission from Ref. [36]. Copyright 2019
American Chemical Society