Facile, Reversible Hydrogen Activation by Low-Coordinate Magnesium Oxide Complexes.

Area of Science:

• Organometallic Chemistry
• Inorganic Chemistry
• Catalysis

Background:

• Facile and reversible dihydrogen activation is crucial for chemical synthesis, catalysis, and hydrogen storage.
• Developing new methods for dihydrogen activation remains a significant challenge in chemistry.

Purpose of the Study:

• To investigate the reactivity of low-coordinate magnesium oxide complexes with dihydrogen.
• To explore the potential of these complexes in catalysis and hydrogen storage.

Main Methods:

• Synthesis and characterization of magnesium oxide complexes [{(RDipnacnac)Mg}2(μ-O)] (1).
• Reaction of complexes 1 with dihydrogen to form mixed hydride-hydroxide complexes [{(RDipnacnac)Mg}2(μ-H)(μ-OH)] (4).
• Computational studies to elucidate the dihydrogen activation mechanism.

Main Results:

• Complexes 1 readily react with dihydrogen under mild conditions to yield complexes 4.
• Dehydrogenation of complexes 4 is ligand-dependent and can be reversed by vacuum degassing (4c to 1c).
• Computational studies indicate an SN2-like nucleophilic attack of the oxide on H2, leading to heterolytic cleavage.

Conclusions:

• Low-coordinate magnesium oxide complexes offer a facile and reversible route for dihydrogen activation.
• These findings have implications for developing new catalysts and materials for hydrogen storage.
• The mechanism involves a unique heterolytic cleavage pathway facilitated by the magnesium oxide core.