Low‐Energy Pathways Found for the NH3 Activation and H2 Elimination by the Werner‐Type Complexes M(NH3)4+ (M=Fe, Ru and Os).

Abstract

AbstractThe interactions of NH3 with the transition metal complexes M(NH3)n+ (M=Fe, Ru, Os; n=0−4) were investigated theoretically with the aim of analyzing the factors that determine their reactivity patterns and product distributions. The reactions of ammonia with the low‐coordination complexes of the three metallic ions (n=1−3) lead only to the addition product M(NH3)n+1+. However, once the highest‐coordinated complex M(NH3)4+ is reached, each of the reactions evolves to metal‐inserted species through low energy channels. For osmium, the hydrogen abstraction from an additional NH3 molecule by the inserted intermediate H−Os(NH3)4‐NH2+ leads to H2 elimination products along a favorable pathway. The facile breaking of the strong N−H bond of ammonia by these Werner‐type complexes is by far the most striking finding emerging from this study. Hopefully, this could inspire future contributions in the areas of chemical and bioinorganic catalysis.