新型均相催化产氢Ru(Ⅱ) NNN配合物的理论预测

An alternative Ru(Ⅱ) NNN complex for catalytic hydrogen production from water: a theoretical prediction

本文提出用NNN配体代替Ru(Ⅱ)PNN配合物中的PNN配体,设计得到Ru(Ⅱ)NNN配合物,并应用密度泛函理论研究该配合物催化分解水产氢的可能性。结果表明:在Ru(Ⅱ)NNN配合物上分解水产氢的机制与在Ru(Ⅱ)PNN配合物上的机制相似,但决定速度步骤的活化能垒降为147.7 kJ/mol,在Ru(Ⅱ)PNN配合物上相应步骤的能垒为157.3 kJ/mol。此外,在Ru(Ⅱ)PNN配合物上该反应为弱吸热反应;但在Ru(Ⅱ)NNN配合物上为弱放热反应,热力学上更有利。因此,可以预测Ru(Ⅱ)NNN配合物具有与Ru(Ⅱ)PNN配合物相同的分解水产氢的催化性能,且催化效果可能更好。

The possibility of catalytic hydrogen production from water on Ru（ Ⅱ） NNN complex designed by replacing the PNN ligand of Ru （ Ⅱ ） PNN complex with the NNN ligand was investigated. Results calculated with density functional theory （DFT） method showed that on the Ru（ Ⅱ ） NNN complex the activation free energy for the rate-determining step,the formation of H2 molecule ,was decreased to 147.7 kJ/mol.By contrast, the activation free energy for the corresponding step on the Ru （ Ⅱ ） PNN complex was 157.3 kJ/mol. Moreover, the overall reaction of H2 production on the Ru （ Ⅱ ） PNN complex was weakly endothermic, but the same reaction on the Ru （ Ⅱ ） NNN complex was weakly exothermic, being more advantageous in thermodynamics.Accordingly,it was suggested that the Ru （ Ⅱ ） NNN complex was a promising catalyst for hydrogen production from water, and its catalytic activity might be better than that of the Ru（ Ⅱ） PNN complex.