On the Demise of PPP-Ligated Iron Catalysts in the Formic Acid Dehydrogenation Reaction
On the Demise of PPP-Ligated Iron Catalysts in the Formic Acid Dehydrogenation Reaction
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DOI：
10.1021/acs.inorgchem.3c03125
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发表时间：
2023-10-31
影响因子：
4.6
通讯作者：
Guan，Hairong
中科院分区：
文献类型：
--
作者：
Pandey，Bedraj;Krause，Jeanette A.;Guan，Hairong
PPP 连接的铁络合物 cis-(iPrPPRP)FeH2(CO) [iPrPPRP = (o-iPr2PC6H4)2PR (R = H 或 Me)] 催化甲酸脱氢成二氧化碳，但随着时间的推移会失去催化活性。本研究重点分析顺式-(iPrPPMeP)FeH2(CO)在催化脱氢反应过程中降解形成的物质。这些降解产物包括在反应介质中可溶和不可溶的物质。分解催化剂的可溶性组分是顺式-[(iPrPPMeP)FeH(CO)2][(HCO2)(HCO2H)x]、质子化的iPrPPMeP和外来O2产生的氧化产物的混合物。沉淀物是溶剂化的 Fe(OCHO)2。进一步的机理研究表明，cis-[(iPrPPMeP)FeH(CO)2][(HCO2)(HCO2H)x] 显示出减弱但可测量的催化活性，可能是通过甲酸根离子置换 CO 配体而实现的。 Fe(OCHO)2 的形成以及 iPrPPMeP 的解离是催化活性最终丧失的原因。
The PPP-ligated iron complexes,cis-(iPrPPRP)FeH2(CO) [iPrPPRP = (o-iPr2PC6H4)2PR (R = H or Me)], catalyze the dehydrogenation of formic acid to carbon dioxide but lose their catalytic activity over time. This study focuses on the analysis of the species formed from the degradation ofcis-(iPrPPMeP)FeH2(CO) over its course of catalyzing the dehydrogenation reaction. These degradation products include species both soluble and insoluble in the reaction medium. The soluble component of the decomposed catalyst is a mixture ofcis-[(iPrPPMeP)FeH(CO)2][(HCO2)(HCO2H)x], protonatediPrPPMeP, and oxidation products resulting from adventitious O2. The precipitate is solvated Fe(OCHO)2. Further mechanistic investigation suggests thatcis-[(iPrPPMeP)FeH(CO)2][(HCO2)(HCO2H)x] displays diminished but measurable catalytic activity, likely through the displacement of a CO ligand by the formate ion. The formation of Fe(OCHO)2along with the dissociation ofiPrPPMeP is responsible for the eventual loss of catalytic activity.