Abstract The reactivity and selectivity of iridium(I) catalysed hydrogen isotope exchange (HIE) reactions can be varied by using wide range of reaction temperatures. Herein, we have done a detailed comparison study with common iridium(I) catalysts (1–6) which will help us to understand and optimize the approaches of either high selectivity or maximum deuterium incorporation. We have demonstrated that the temperature window for these studied iridium(I) catalysts is surprisingly very broad. This principle was further proven in some HIE reactions on complex drug molecules.
