Role of Water, CO2, and Noninnocent Ligands in the CO2 Hydrogenation to Formate by an Ir(III) PNP Pincer Catalyst Evaluated by Static-DFT and ab Initio Molecular Dynamics under Reaction Conditions,Organometallics

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Role of Water, CO2, and Noninnocent Ligands in the CO2 Hydrogenation to Formate by an Ir(III) PNP Pincer Catalyst Evaluated by Static-DFT and ab Initio Molecular Dynamics under Reaction Conditions
Organometallics ( IF 2.5 ) Pub Date : 2017-12-07 00:00:00 , DOI: 10.1021/acs.organomet.7b00761
C. S. Praveen _{1,

2} , Aleix Comas-Vives ₂ , Christophe Copéret ₂ , J. VandeVondele ₁

Affiliation

Reaction pathways relevant to the CO₂ hydrogenation to formate using a homogeneous Ir^IIIH₃(PNP) pincer catalyst have been investigated using static DFT calculations and ab initio molecular dynamics simulations under reaction conditions. The role of a base, solvent, and the noninnocent ligand are demonstrated. Static DFT calculations with an implicit solvent highlight the importance of selecting a highly polar solvent. The insertion of CO₂ and regeneration of the catalyst are identified as the key steps in the reaction mechanism. Unlike in the static DFT calculations, the AIMD simulations show that an additional CO₂ molecule and explicit water molecules can expedite the direct cleavage of the H₂ coordinated to the metal center to regenerate the catalyst. In addition, the AIMD simulations indicate that the pyridine ring does not participate in the hydrogenation mechanism, while the α-carbon at the pyridine ring is very acidic and participates in off-cycle reactions.

中文翻译：

在反应条件下，通过静态DFT和从头算分子动力学评估水，CO ₂和非纯配体在Ir（III）PNP夹钳催化剂中CO ₂加氢生成甲酸酯中的作用

使用静态DFT计算和反应条件下的从头算分子动力学模拟，研究了与使用均相Ir ^III H ₃（PNP）钳型催化剂进行CO ₂加氢生成甲酸酯有关的反应途径。证明了碱，溶剂和非纯配体的作用。使用隐式溶剂的静态DFT计算突显了选择高极性溶剂的重要性。CO ₂的插入和催化剂的再生被确定为反应机理中的关键步骤。与静态DFT计算不同，AIMD模拟表明，额外的CO ₂分子和显性水分子可以加速H ₂的直接裂解。与金属中心配合使催化剂再生。另外，AIMD模拟表明吡啶环不参与氢化机理，而吡啶环处的α-碳非常酸性并且参与了脱环反应。

更新日期：2017-12-07

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