Capturing Hydrogen Radicals by Neutral Metal Hydroxides

Abstract

Capturing the hydrogen radical is of central importance in various systems ranging from catalysis to biology to astronomy, but it has been proven to be challenging experimentally because of its high reactivity and short lifetime. Here, neutral MO 3 H 4 (M = Sc, Y, La) complexes were characterized by size-specific infrared-vacuum ultraviolet spectroscopy. All these products were determined to be the hydrogen radical adducts in the form of H•M(OH) 3 . The results indicate that the addition of the hydrogen radical to the M(OH) 3 complex is both thermodynamically exothermic and kinetically facile in the gas phase. Moreover, the soft collisions in the cluster growth channel with the helium expansion were found to be demanded for the formation of H•M(OH) 3 . This work highlights the pivotal roles played by the soft collisions in the formation of hydrogen radical adducts and also opens new avenues toward the design and chemical control of compounds.

Infrared spectroscopic study of solvation and size effects on reactions between water molecules and neutral rare-earth metals

“…The mechanism for kinetically trapping H˙Sc(OH) 3 by the soft helium expansion has been recently discussed in detail. 30 The H˙Sc(OH) 3 complex combines with the water molecule to form the target product ScO 4 H 6 (H˙Sc(OH) 3 (H 2 O), isomer 1B), which is exothermic by 16.3 kcal mol −1 .…”

“…Considering that H˙Sc(OH) 3 and OH radicals are also generated in the laser–vaporization process, 30,34 Sc 2 O 6 H 7 might also be formed via reactions (1) and (2).H˙Sc(OH) 3 + Sc → Sc 2 O 3 H 4 Sc 2 O 3 H 4 + 3OH → Sc 2 O 6 H 7 …”

“…30,31 using size-specic infrared-vacuum ultraviolet (IR-VUV) spectroscopy, in which MO 3 H 4 has a hydrogen radical structure and M 2 O 4 H 4 has a water-split structure. In this work, we increased the number of water molecules to study the solvation and size effects on the reactions between water with neutral rare-earth metals.…”

Deoxygenative arylation of secondary amides by merging iridium catalysis with electrochemical radical cross-coupling

“…6 Moreover, with the development of photocatalysis, the combination of the photochemical radical process with deoxygenative functionalization of amides has been successfully achieved independently by the Dixon group (Scheme 1a-ii) 7 and our group. 8 Recently, organic electrosynthesis has become a versatile and powerful method in organic synthesis, and a variety of electrochemical C–C bond cross-coupling reactions have been disclosed. 9,10 However, the application of organic electrosynthesis in deoxygenative functionalization of amides has not been reported yet (Scheme 1a-iii), despite the advantages of sustainability and atom economy compared with conventional methods.…”

“…As an ongoing effort towards our development of efficient procedures for the deoxygenative functionalization of amides, 6,8 we envisioned that the combination of amide reduction with the electrocatalytic process might provide a highly efficient and alternative route to amines from these widely available yet inert raw materials. In this context, inspired by the direct arylation of imines with aryl nitriles via radical–radical cross-coupling strategies, 12 we envisioned that by the merging of electrochemical radical cross-coupling of aryl nitriles with semi-reduction of inert amides, the direct reductive arylation of amides may be achieved, to afford the corresponding benzylic amines that are important structural motifs in many natural products, biologically active compounds and pharmaceutical agents (Scheme 1b).…”