In ate-complexes, i.e. coordination complexes with a negative charge cen- ter, all the ligands are anionically activated and hydrogen atoms bound to IX-or -carbon are hydride-mobile. This hypothesis is substantiated, in cor- relation with known onium-complexes which behave in the opposite way, by aseries of typical examples, or is brought into the discussion as to whether short-lived, i.e. non-isolable, ate-complexes are involved in the reaction...