Computational Evaluation of Potential Molecular Catalysts for Nitrous Oxide Decomposition
Computational Evaluation of Potential Molecular Catalysts for Nitrous Oxide Decomposition
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一氧化二氮分解的潜在分子催化剂的计算评估
DOI：
10.1021/acs.inorgchem.2c01598
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发表时间：
2022
影响因子：
4.6
通讯作者：
Shao, Yihan
中科院分区：
文献类型：
--
作者：
Nicholas, Kenneth M.;Lander, Chance;Shao, Yihan
一氧化二氮（N2 O）是一种强效温室气体（GHG），作为轻度麻醉剂的用途有限，反应性不发达。一氧化二氮的分解（分解）对于作为温室气体的缓解至关重要。虽然N2 O分解的非均相催化剂已经被开发出来，但仍然需要高效、长寿命的固体催化剂，并且催化途径的细节还没有很好地理解。本文报道的是用于N2 O裂解的三种潜在分子（均相）催化剂的计算评估，其可以帮助开发更活性和更稳健的催化剂并提供更深的机理见解：一种基于Cu（I）的[（CF 3 O）4Al]Cu（A-1），以及两种基于Ru（III）的Cl（POR）Ru（B-1）和（NTA）Ru（C-1）（POR =卟啉，NTA =次氮基三乙酸酯）。根据两阶段反应途径评估潜在中间体和关键过渡态的结构和能量可行性：（A）脱氧（DO），在此期间金属-N2 O络合物经历N-O键断裂以产生N2和金属-氧物种，和（B）（二）氧释放（OER），其中金属-氧物种二聚成二金属-过氧络合物，随后转化为金属-分子氧物质，分子氧从该金属-分子氧物质解离。对于（F-L）Cu（I）活化剂（A-1），通过O键合的（F-L）Cu-O-N2或更好地通过双金属N，O键合的（F-L）Cu-NNO-Cu（F-L）络合物促进N2 O的脱氧;所得的铜氧基（F-L）Cu-O被放热转化为（F-L）Cu-（η2，η2-O2）-Cu（F-L），这导致有利于解离O2的双氧物质（F-L）Cu（η2-O2）。（POR）ClRu（B-1）的DO/OER过程的关键特征包括吸能N2 O配位、N2从LR′ u-N2 O-RuL到Cl（POR）RuO的容易的析出、Cl（POR）RuO到过氧Cl（POR）Ru（O2）Ru（POR）Cl的适度势垒耦合以及Cl（POR）Ru（η1-O2）的最终O2解离，这是近热中性的。（NTA）Ru（III）（C-1）促进的N2 O分解可以通过放能N2 O配位进行，易于N2从（NTA）Ru-ON 2或（NTA）Ru-N2 O-Ru（NTA）解离形成（NTA）Ru-O;（NTA）Ru-氧代物种的二聚易于产生（NTA）Ru-O-O-Ru（NTA），并且随后来自过氧物种的OE是适度的吸能。考虑到整体能量学，（F-L）Cu和Cl（POR）Ru衍生物被认为是促进容易的N2 O分解的最佳候选物。
Nitrous oxide (N2O) is a potent greenhouse gas (GHG) with limited use as a mild anesthetic and underdeveloped reactivity. Nitrous oxide splitting (decomposition) is critical to its mitigation as a GHG. Although heterogeneous catalysts for N2O decomposition have been developed, highly efficient, long-lived solid catalysts are still needed, and the details of the catalytic pathways are not well understood. Reported herein is a computational evaluation of three potential molecular (homogeneous) catalysts for N2O splitting, which could aid in the development of more active and robust catalysts and provide deeper mechanistic insights: one Cu(I)-based, [(CF3O)4Al]Cu (A-1), and two Ru(III)-based, Cl(POR)Ru (B-1) and (NTA)Ru (C-1) (POR = porphyrin, NTA = nitrilotriacetate). The structures and energetic viability of potential intermediates and key transition states are evaluated according to a two-stage reaction pathway: (A) deoxygenation (DO), during which a metal–N2O complex undergoes N–O bond cleavage to produce N2and a metal–oxo species and (B) (di)oxygen evolution (OER), in which the metal–oxo species dimerizes to a dimetal–peroxo complex, followed by conversion to a metal–dioxygen species from which dioxygen dissociates. For the (F–L)Cu(I) activator (A-1), deoxygenation of N2O is facilitated by anO-bound (F–L)Cu–O–N2or better by a bimetallicN,O-bonded, (F–L)Cu–NNO–Cu(F–L) complex; the resulting copper–oxyl (F–L)Cu–O is converted exergonically to (F–L)Cu–(η2,η2-O2)–Cu(F–L), which leads to dioxygen species (F–L)Cu(η2-O2), that favorably dissociates O2. Key features of the DO/OER process for (POR)ClRu (B-1) include endergonic N2O coordination, facile N2evolution from LR′u–N2O–RuL to Cl(POR)RuO, moderate barrier coupling of Cl(POR)RuO to peroxo Cl(POR)Ru(O2)Ru(POR)Cl, and eventual O2dissociation from Cl(POR)Ru(η1-O2), which is nearly thermoneutral. N2O decomposition promoted by (NTA)Ru(III) (C-1) can proceed with exergonic N2O coordination, facile N2dissociation from (NTA)Ru–ON2or (NTA)Ru–N2O–Ru(NTA) to form (NTA)Ru–O; dimerization of the (NTA)Ru-oxo species is facile to produce (NTA)Ru–O–O–Ru(NTA), and subsequent OE from the peroxo species is moderately endergonic. Considering the overall energetics, (F–L)Cu and Cl(POR)Ru derivatives are deemed the best candidates for promoting facile N2O decomposition.