氧原子转移作为氧-氧键形成的替代途径。,Inorganic Chemistry

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氧原子转移作为氧-氧键形成的替代途径。
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2020-04-21 , DOI: 10.1021/acs.inorgchem.9b03751
Mehmed Z Ertem ₁ , Javier J Concepcion ₁

Affiliation

对水氧化催化机理的基本了解是设计和开发高效耐用的水氧化催化剂的先决条件。在这项工作中，[RuII（npm）（4-pic）2（H2O）] 2+（npm = 4-叔丁基-2,6-di（1'， 8'-萘啶-2'-基）-吡啶，pic = 4-picoline）络合物[RuII-OH2] 2+，揭示了氧原子从高反应性钌氧代中间体转移到配体的非配位氮原子的新途径通过在配体骨架上存储氧化当量作为N-氧化物基团来释放氧气。理论计算表明，最初的络合物[RuII-OH2] 2+在氧化后通过来自RuV = O物种的简便OAT步骤被氧化成二氧化氮[RuII-OH2，（-NO）2] 2+络合物。并且[RuV = O，（-NO）2] 3+表示最重要的OO键形成反应。此外，引入了一种新的逐步释放氧气的机理，该机理是通过Ru-O和NO部分的偶联产生过氧化物中间体[RuV-OO-N，（-NO）] 3+来进行的，并且可以与亲水分子竞争氧释放反应的攻击途径。按照这种机理，水分子被氧化活化为“氧原子”，该氧原子“存储”在非配位吡啶上。中间氮氧化物的配位膨胀促进了第二个水分子的氧化活化，产生了产生双氧分子所需的第二个氧原子。其通过Ru-O和NO部分的偶联进行，产生过氧化物中间体[RuV-OO-N，（-NO）] 3+，并且可以与水亲核进攻途径竞争氧释放反应。按照这种机理，水分子被氧化活化为“氧原子”，该氧原子“存储”在非配位吡啶上。中间氮氧化物的配位膨胀促进了第二个水分子的氧化活化，产生了产生双氧分子所需的第二个氧原子。其通过Ru-O和NO部分的偶联进行，产生过氧化物中间体[RuV-OO-N，（-NO）] 3+，并且可以与水亲核进攻途径竞争氧释放反应。按照这种机理，水分子被氧化活化为“氧原子”，该氧原子“存储”在非配位吡啶上。中间氮氧化物的配位膨胀促进了第二个水分子的氧化活化，产生了产生双氧分子所需的第二个氧原子。在非配位吡啶上。中间氮氧化物的配位膨胀促进了第二个水分子的氧化活化，产生了产生双氧分子所需的第二个氧原子。在非配位吡啶上。中间氮氧化物的配位膨胀促进了第二个水分子的氧化活化，产生了产生双氧分子所需的第二个氧原子。

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Oxygen Atom Transfer as an Alternative Pathway for Oxygen-Oxygen Bond Formation.

Fundamental understanding of catalytic mechanisms of water oxidation is a prerequisite for the design and development of efficient and rugged water oxidation catalysts. In this work, a detailed mechanistic study of the water oxidation mechanism of the [RuII(npm)(4-pic)2(H2O)]2+ (npm = 4-t-butyl-2,6-di(1',8'-naphthyrid-2'-yl)-pyridine, pic = 4-picoline) complex, [RuII-OH2]2+, reveals oxygen atom transfer from highly reactive ruthenium oxo intermediates to noncoordinating nitrogen atoms of the ligand as a novel route for oxygen evolution via storage of oxidizing equivalents as N-oxide groups on the ligand framework. Theoretical calculations show that the initial complex, [RuII-OH2]2+, is transformed to a di-N-oxide [RuII-OH2,(-NO)2]2+ complex upon oxidation via facile OAT steps from RuV=O species and that [RuV=O,(-NO)2]3+ represents the most likely reactive species for the critical O-O bond formation. Furthermore, a new stepwise mechanism for oxygen evolution is introduced, which proceeds via coupling of Ru-O and N-O moieties producing a peroxide intermediate, [RuV-OO-N,(-NO)]3+, and can compete with the water nucleophilic attack pathway for the oxygen evolution reaction. In this mechanism, a water molecule is oxidatively activated to an "oxygen atom" which is "stored" at a noncoordinating pyridine. Oxidative activation of a second water molecule, facilitated by coordination expansion of the intermediate N-oxide, generates the second oxygen atom required to produce a dioxygen molecule.

更新日期：2020-04-21

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