The mechanisms of H–H and N–H bond cleavages of dihydrogen and ammonia mediated by the diiridium μ₂-imido complex [(Cp*Ir)₂(μ₂-H)(μ₂-NH)]⁺ (A; Cp* = η⁵-C₅Me₅) were theoretically investigated with the density functional theory (DFT) method. Both oxidative addition and metal–ligand cooperation modes have been studied for H–H and N–H bond cleavages, respectively. The H–H bond cleavage most likely occurs through competitive oxidative addition and metal–ligand cooperation, and both cleavage modes have similar overall free energy barriers (24.3 and 25.7 kcal/mol, respectively). The ligand-assisted N–H bond heterolytic cleavage mechanism is proposed for the NH₃ reaction, and the general oxidative addition pathway can be reasonably ruled out, as it is kinetically unfavorable.

中文翻译：

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双功能亚氨基（NH）桥接的二铱配合物对氢和氨的H–H和N–H键裂解：DFT研究

二氢和氨的H-H和N-H键断裂的由二铱介导率μ的机制₂ -imido络合物[（CP * Ir）的₂（μ ₂ -H）（μ ₂ -NH）] ⁺（甲的Cp; * =η ⁵ -C ₅我₅）用密度泛函理论（DFT）方法进行了理论研究。分别研究了H–H和N–H键断裂的氧化加成和金属-配体配合模式。H–H键的裂解很可能是通过竞争性氧化加成和金属-配体的协同作用发生的，并且两种裂解模式的总自由能垒相似（分别为24.3和25.7 kcal / mol）。提出了用于NH ₃反应的配体辅助的NH键杂化裂解机理，由于其在动力学上是不利的，因此可以合理地排除一般的氧化加成途径。