Metal‐Templated, Tight Loop Conformation of a Cys‐X‐Cys Biomimetic Assembles a Dimanganese Complex
Metal‐Templated, Tight Loop Conformation of a Cys‐X‐Cys Biomimetic Assembles a Dimanganese Complex
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金属-Cys-X-Cys 仿生紧密环构象组装二锰络合物
DOI：
10.1002/anie.201913259
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Darensbourg, Marcetta Y.
中科院分区：
文献类型：
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作者：
Le, Trung;Nguyen, Hao;Perez, Lisa M.;Darensbourg, Donald J.;Darensbourg, Marcetta Y.
为了生成MN 2S 2-Mn（CO）3Br的阴离子类似物，我们将金属二硫代配体MN 2S 22-引入Mn（CO）5 Br，该配体由Cys-X-Cys仿生物ema 4-配体（ema=N，N′-亚乙基双（巯基乙酰胺）; M=NiII，[VIV] O]2+和FeIII）制备。一个意想不到的，非常稳定的二锰产物，（H2 N2（CH 2C =O（μ-S））2）[Mn（CO）3] 2，是由于原本存在于N2 S24 −口袋中的M的丢失，被酰胺氮的质子化所取代，产生H2 ema 2 −。因此，ema配体已经将其配位模式从容纳单个金属的N2 S24 −空腔转换为双核H2 ema 2 −，在Mn-μ-S-CH 2-C-O，5元环内具有桥连硫和羧酰胺氧。通过锌离子的原位金属模板化给出Mn 2产物的定量产率。通过计算研究，我们比较了“线性”ema 4 −与在单个金属周围“紧环”中冷冻的ema 4 −的构象，以及H2 ema 2 −可能的“松散”折叠，这是双核的最佳排列。XRD分子结构显示固态下酰胺基氮质子处存在大量氢键。
With the goal of generating anionic analogues to MN2S2⋅Mn(CO)3Br we introduced metallodithiolate ligands, MN2S22−prepared from the Cys‐X‐Cys biomimetic, ema4−ligand (ema=N,N′‐ethylenebis(mercaptoacetamide); M=NiII, [VIV≡O]2+and FeIII) to Mn(CO)5Br. An unexpected, remarkably stable dimanganese product, (H2N2(CH2C=O(μ‐S))2)[Mn(CO)3]2resulted from loss of M originally residing in the N2S24−pocket, replaced by protonation at the amido nitrogens, generating H2ema2−. Accordingly, the ema ligand has switched its coordination mode from an N2S24−cavity holding a single metal, to a binucleating H2ema2−with bridging sulfurs and carboxamide oxygens within Mn‐μ‐S‐CH2‐C‐O, 5‐membered rings. In situ metal‐templating by zinc ions gives quantitative yields of the Mn2product. By computational studies we compared the conformations of “linear” ema4−to ema4−frozen in the “tight‐loop” around single metals, and to the “looser” fold possible for H2ema2−that is the optimal arrangement for binucleation. XRD molecular structures show extensive H‐bonding at the amido‐nitrogen protons in the solid state.