Reactivity of Cr+(6S,4D), Mn+(7S,5S), and Fe+(6D,4F): Reaction of Cr+, Mn+, and Fe+ with Water

Abstract

The study of the reaction of water with the first-row transition-metal ions is continued in this work. Here we report the study of the reaction of water with the middle (Cr+, Mn+, and Fe+) first-row transition-metal cations in both high- and low-spin states. In agreement with experimental observations, the oxides are predicted to be more reactive than the metal ions, and no exothermic products are observed. Formation of endothermic products is examined. An in-depth analysis of the reaction paths leading to the observed products is given, including various minima, and several important transition states. All results have been compared with existing experimental and theoretical data, and our earlier works covering the (Sc+, Ti+, V+) + H2O reactions to observe existent trends for the early first-row transition-metal ions. The MO+ + H2 energy relative to M+ + H2O increases through the series from left to right. Additionally, the Fe+ case is seen to be significantly different from the entire Sc+−Mn+ series because both its low- and high-spin cases involve paired electrons, and Mn+ shows some differences because of the complete half-filling of its valence shell in the high-spin case.