Dioxygen Activation and Mandelate Decarboxylation by Iron(II) Complexes of N4 Ligands: Evidence for Dioxygen-Derived Intermediates from Cobalt Analogues
Dioxygen Activation and Mandelate Decarboxylation by Iron(II) Complexes of N4 Ligands: Evidence for Dioxygen-Derived Intermediates from Cobalt Analogues
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N4 配体的铁 (II) 配合物引起的分子氧活化和扁桃酸脱羧：来自钴类似物的分子氧衍生中间体的证据
DOI：
10.1021/acs.inorgchem.2c01308
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发表时间：
2022
影响因子：
4.6
通讯作者：
and Tapan Kanti Paine
中科院分区：
文献类型：
--
作者：
Rahul Dev Jana;Biswarup Chakraborty;Sayantan Paria;Takehiro Ohta;Reena Singh;Sourav Mandal;Satadal Paul;Shinobu Itoh;and Tapan Kanti Paine
单体 [(TPA)MII(扁桃酸)]+(M = Fe,1; Co,3) 和二聚体 [(BPMEN)2MII2(μ-扁桃酸)2]2+(M = Fe,2; Co,4) (TPA = 三(2-吡啶甲基)胺和 BPMEN 的分离、表征和双氧反应性报道了=N1,N2-二甲基-N1,N2-双(吡啶-2-基-甲基)乙烷-1,2-二胺)络合物。扁桃酸铁(II)-和钴(II)-络合物与分子氧反应，以1:1的比例生成苯甲醛和苯甲酸。在反应中，分子氧中的一个氧原子被引入苯甲酸中，但苯甲醛不会从分子氧中衍生出任何氧原子。虽然在铁(II)-扁桃酸络合物中没有观察到O2衍生的中间体，但类似的钴(II)络合物在低温(-80°C)下与双氧反应生成相应的钴(III)-超氧物种(S)，这是与扁桃酸脱羧启动有关的关键中间体。在-20 °C 时，钴(II)-扁桃酸络合物可逆地结合双氧，导致形成μ-1,2-过氧二钴(III)-扁桃酸物质(P)。 O2 衍生中间体 (SandP) 的几何和电子结构已通过计算研究确定。中间体SandPupon用质子酸处理进行脱羧，得到苯甲醛（50%），同时形成相应的μ-1,2-过氧-μ-扁桃酸二钴（III）（P1）物质。从钴(II)-羧酸盐络合物[(TPA)CoII(MPA)]+(5) (MPA = 2-甲氧基苯乙酸酯)中分离出的过氧化物物质的晶体结构支持P1的组成。对钴配合物中分子氧衍生中间体的观察及其电子结构分析不仅提供了有关扁桃酸脱羧过程中活性物质性质的信息，而且还揭示了分子氧双电子与四电子还原的机制途径。
The isolation, characterization, and dioxygen reactivity of monomeric [(TPA)MII(mandelate)]+(M = Fe,1; Co,3) and dimeric [(BPMEN)2MII2(μ-mandelate)2]2+(M = Fe,2; Co,4) (TPA = tris(2-pyridylmethyl)amine and BPMEN =N1,N2-dimethyl-N1,N2-bis(pyridin-2-yl-methyl)ethane-1,2-diamine) complexes are reported. The iron(II)- and cobalt(II)-mandelate complexes react with dioxygen to afford benzaldehyde and benzoic acid in a 1:1 ratio. In the reactions, one oxygen atom from dioxygen is incorporated into benzoic acid, but benzaldehyde does not derive any oxygen atom from dioxygen. While no O2-derived intermediate is observed with the iron(II)-mandelate complexes, the analogous cobalt(II) complexes react with dioxygen at a low temperature (−80 °C) to generate the corresponding cobalt(III)-superoxo species (S), a key intermediate implicated in the initiation of mandelate decarboxylation. At −20 °C, the cobalt(II)-mandelate complexes bind dioxygen reversibly leading to the formation of μ-1,2-peroxo-dicobalt(III)-mandelate species (P). The geometric and electronic structures of the O2-derived intermediates (SandP) have been established by computational studies. The intermediatesSandPupon treatment with a protic acid undergo decarboxylation to afford benzaldehyde (50%) with a concomitant formation of the corresponding μ-1,2-peroxo-μ-mandelate-dicobalt(III) (P1) species. The crystal structure of a peroxide species isolated from the cobalt(II)-carboxylate complex [(TPA)CoII(MPA)]+(5) (MPA = 2-methoxyphenylacetate) supports the composition ofP1. The observations of the dioxygen-derived intermediates from cobalt complexes and their electronic structure analyses not only provide information about the nature of active species involved in the decarboxylation of mandelate but also shed light on the mechanistic pathway of two-electron versus four-electron reduction of dioxygen.