Perchlorate reduction catalyzed by dioxidomolybdenum(VI) complexes: Effect of ligand substituents

Iron-Catalyzed C–H Oxygenation Using Perchlorate Enabled by Secondary Sphere Hydrogen Bonds

“…The atypical UV−vis result prompted us to examine the feasibility of ClO 4 − reduction in analogy to prior reports. [9][10][11][12][13]25,26 The UV−vis experiment described above was repeated with three variations. First, introduction of 4.0 equiv of an O-atom acceptor (PPh 3 ) caused only slight changes to the UV−vis spectrum when added 18 h after [NBu 4 ][ClO 4 ] and did not bleach the absorbance when added after 5 min.…”

“…9−11 Another important example is a Mo(VI)O 2 precatalyst reported by Mosch-Zanetti and co-workers (Figure 1a). 12,13 In both cases, phosphine or thioether substrates, which form strong O�PPh 3 or O�SR 2 bonds, are used as terminal O-atom acceptors. Similar catalyst designs have been employed with heterogeneous systems using Pd/C supports for ClO 4 − reduction in aqueous media using H 2 (Figure 1a).…”

Reactivity of metal dioxo complexes

“…Complex 2 has also been shown to reduce perchlorate to chloride using four equivalents of triphenylphosphine. 47,48 Scandium and other Lewis acid additives have increased the turnover numbers in similar molybdenum dioxo complexes, affording yields surpassing 80%. 49 Molybdenum dioxo catalyzed nitrate reduction can be performed using thioethers as oxygen acceptors.…”

Dioxygen Activation by a Bioinspired Tungsten(IV) Complex

“… 1 − 5 The major drawback of molybdenum OAT catalysts is their high tendency to form relatively inert molybdenum(V) μ-oxo dimers, which appear as a result of comproportionation of molybdenum(IV) oxido and molybdenum(VI) dioxido species. 6 − 8 The dinucleation can be inhibited by increasing the steric bulk of the ligands 9 or immobilizing the active species to a polymeric support. 10 Analogous dimers are rare in tungsten chemistry due to the low redox potential of tungsten(VI) dioxido moieties.…”

“…Over the past decades, tungsten­(VI) and especially molybdenum­(VI) dioxido motifs have drawn much attention as models for different metalloenzymes which catalyze oxygen atom transfer (OAT) reactions. − The major drawback of molybdenum OAT catalysts is their high tendency to form relatively inert molybdenum­(V) μ-oxo dimers, which appear as a result of comproportionation of molybdenum­(IV) oxido and molybdenum­(VI) dioxido species. − The dinucleation can be inhibited by increasing the steric bulk of the ligands or immobilizing the active species to a polymeric support . Analogous dimers are rare in tungsten chemistry due to the low redox potential of tungsten­(VI) dioxido moieties. − Although some of the tungsten complexes turned out as bioinorganic models and catalysts for oxygenation reactions, those reactions have a low atom economy since the presence of terminal oxidants such as peroxides is always required. , Thus, investigating systems that utilize dioxygen or even air is highly desirable for economic and environmental reasons .…”