Cooperative redox and spin activity from three redox congeners of sulfur-bridged iron nitrosyl and nickel dithiolene complexes.
Cooperative redox and spin activity from three redox congeners of sulfur-bridged iron nitrosyl and nickel dithiolene complexes.
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DOI：
10.1073/pnas.2201240119
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发表时间：
2022-06-21
影响因子：
11.1
通讯作者：
中科院分区：
文献类型：
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作者：
大自然的策略是在富含地球的过渡金属中产生氧化还原活性，使它们能够与贵金属竞争催化王的地位，包括将两种或两种以上的金属放置在非常接近的位置，以及电子离域的影响，这些分子附加物是非无害的，如悬垂的铁硫簇合物和二硫代烯。一种受到生物启发的铁和镍络合物的合成应用了这两种策略，就像在氢酶活性中心中发现的那样：一氧化氮被用作铁的氧化还原活性成分，铁是硫桥联到镍二硫杂环烯上的。伴随着微小的结构变化，意味着添加或移除电子的电荷轨迹，是由电子态布居和自旋耦合引起的令人印象深刻的磁差异。硫桥联铁镍杂双金属化合物的合成灵感来自于大自然的策略，即“诱骗”丰富的第一排过渡金属来实现双电子过程：氧化还原活性配体(包括悬挂的铁-硫原子簇)和近端金属。我们的设计是在每种金属上都有氧化还原活性的配体，在铁上没有，在镍上有二硫杂烯，结果观察到了出人意料的复杂的物理性质。金属二硫酸盐(NO)Fe(N2S2)与不稳定的配体[NiII(S2C2Ph2)]0，NiDT反应，生成预期的S桥联的中性加合物FeNi，含有二重态{Fe(NO)}7。FeNi的两个氧化还原事件具有良好的可逆性，导致分离出还原和氧化的同系物。各种光谱和单晶X射线衍射的表征结果表明，FeNi母体的还原生成了[FeNi]−，这是一种罕见的高自旋{Fe(NO)}8，被描述为线性FeII(NO-)。穆斯堡尔数据对{Fe(NO)}7/8位的氧化还原变化具有诊断作用。FeNi的氧化在溶液中产生2[FeNi]+⇌[Fe2Ni2]2+平衡；结晶只产生[Fe2Ni2]2+二聚体，分离为Pf6−和Barf−盐。单体是位于{Fe(NO)}7和NiDT+之间的自旋耦合的双自由基团，而二聚反应则通过Ni2S2菱体将两个NiDT+偶联。对二聚体的磁化率研究发现，该二聚体在300K时为单重态，具有热可及的三重态激发态(χMT=0.67emu·K·−1，µEff=2.31µB)，并可在20~50K下用平行模电子顺磁共振光谱检测到。建立在H4链上的理论模型解释了这种意外的低能三重态，这种低能三重态是由四自由基分子集团的反磁和铁磁耦合引起的。
Nature’s strategies for engendering redox activity in earth-abundant transition metals, permitting them to compete with noble metals as kings of catalysis, include the positioning of two or more metals in close proximity and the effects of electron-delocalizing, “noninnocent” molecular addenda such as pendant iron–sulfur clusters and dithiolenes. A bioinspired synthesis of complexes of iron and nickel has applied both strategies, as found in hydrogenase active sites: nitric oxide is used as a redox-active constituent on iron that is sulfur-bridged to a nickel dithiolene. Concomitant with minor structural changes that signify the loci of charge from added or removed electrons are impressive magnetic differences resulting from population of electronic states and spin coupling. The synthesis of sulfur-bridged Fe–Ni heterobimetallics was inspired by Nature’s strategies to “trick” abundant first row transition metals into enabling 2-electron processes: redox-active ligands (including pendant iron–sulfur clusters) and proximal metals. Our design to have redox-active ligands on each metal, NO on iron and dithiolene on nickel, resulted in the observation of unexpectedly intricate physical properties. The metallodithiolate, (NO)Fe(N2S2), reacts with a labile ligand derivative of [NiII(S2C2Ph2)]0, NiDT, yielding the expected S-bridged neutral adduct, FeNi, containing a doublet {Fe(NO)}7. Good reversibility of two redox events of FeNi led to isolation of reduced and oxidized congeners. Characterization by various spectroscopies and single-crystal X-ray diffraction concluded that reduction of the FeNi parent yielded [FeNi]−, a rare example of a high-spin {Fe(NO)}8, described as linear FeII(NO–). Mössbauer data is diagnostic for the redox change at the {Fe(NO)}7/8 site. Oxidation of FeNi generated the 2[FeNi]+⇌[Fe2Ni2]2+ equilibrium in solution; crystallization yields only the [Fe2Ni2]2+ dimer, isolated as PF6− and BArF− salts. The monomer is a spin-coupled diradical between {Fe(NO)}7 and NiDT+, while dimerization couples the two NiDT+ via a Ni2S2 rhomb. Magnetic susceptibility studies on the dimer found a singlet ground state with a thermally accessible triplet excited state responsible for the magnetism at 300 K (χMT = 0.67 emu·K·mol−1, µeff = 2.31 µB), and detectable by parallel-mode EPR spectroscopy at 20 to 50 K. A theoretical model built on an H4 chain explains this unexpected low energy triplet state arising from a combination of anti- and ferromagnetic coupling of a four-radical molecular conglomerate.
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影响因子：
8.4
作者：
Clarke RM;Jeen T;Rigo S;Thompson JR;Kaake LG;Thomas F;Storr T
通讯作者：
Storr T
DOI：
10.1126/science.abc3183
发表时间：
2020-08-14
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Bullock RM;Chen JG;Gagliardi L;Chirik PJ;Farha OK;Hendon CH;Jones CW;Keith JA;Klosin J;Minteer SD;Morris RH;Radosevich AT;Rauchfuss TB;Strotman NA;Vojvodic A;Ward TR;Yang JY;Surendranath Y
通讯作者：
Surendranath Y
影响因子：
4.6
作者：
Arumugam, Kuppuswamy;Selvachandran, Malathy;Donahue, James P.
通讯作者：
Donahue, James P.
影响因子：
4.6
作者：
Chen, HY;Collomb, MN;Brudvig, GW
通讯作者：
Brudvig, GW
影响因子：
4.6
作者：
COTTON, FA;SU, JN;CHEN, H
通讯作者：
CHEN, H