Hydration of Carbonyl Groups: The Labile H3O+ Ion as an Intermediate Modulated by the Surrounding Water Molecules

A step dance: Extensive cluster continuum model calculations verify that the stepwise hydration of a carbonyl group (see scheme: O red, H yellow, C gray) is more favorable than the widely suggested concerted pathway. It is also shown that for reliable calculations on the water-mediated proton transfer a large basis set and a suitable cluster continuum model are required.