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Gold CO and CO2 complexes and their role in hydrogen generation

The so-called Water-Gas Shift (WGS) reaction is an important catalytic route to hydrogen generation. It converts CO and water into CO2 and H2. Heterogeneous gold catalysts are highly active for WGS but the mechanism remains a matter of debate.

In a recent Science Advances paper, the groups of Professor Manfred Bochmann and Dr Joseph Wright (DFT calculations) describe the first examples of isolable CO and CO2 complexes of gold(III) and show how CO insertion can lead to the formation of hydride together with CO2. Gold(III) and platinum(II) are isoelectronic, but whereas CO complexes of platinum were first reported in 1869, all attempts to make analogous gold(III) CO complexes resulted in the formation of gold nanoparticles. It has now been shown that with the help of rigid pincer ligands, Au(III)-CO complexes are indeed isolable, and further, that the way in which CO binds to gold differs significantly from the bonding to platinum, which explains the drastic reactivity differences between the CO complexes of these closely related elements.