Structural Diversities in Heterometallic Mn–Ca Cluster Chemistry from the Use of Salicylhydroxamic Acid: {MnIII4Ca2}, {MnII/III6Ca2}, {MnIII/IV8Ca}, and {MnIII8Ca2} Complexes with Relevance to Both High- and Low-Valent States of the Oxygen-Evolving Complex
| Autor: | Sayak Das Gupta, Evangelia S. Koumousi, Alysha A. Alaimo, Vassilis Psycharis, Chaoran Li, Laura J. McCormick, Luís Cunha-Silva, Theocharis C. Stamatatos, Simon J. Teat, Shreya Mukherjee, Catherine P. Raptopoulou, George Christou, Albert Escuer |
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| Rok vydání: | 2017 |
| Předmět: |
010405 organic chemistry
Stereochemistry Chemistry Cluster chemistry Bridging ligand Bioinorganic chemistry 010402 general chemistry 01 natural sciences Tautomer Magnetic susceptibility 0104 chemical sciences Inorganic Chemistry Metal Crystallography Catalytic cycle Octahedron visual_art visual_art.visual_art_medium Physical and Theoretical Chemistry |
| Zdroj: | Alaimo, AA; Koumousi, ES; Cunha-Silva, L; McCormick, LJ; Teat, SJ; Psycharis, V; et al.(2017). Structural Diversities in Heterometallic Mn-Ca Cluster Chemistry from the Use of Salicylhydroxamic Acid: {MnIII4Ca2}, {MnII/III6Ca2}, {MnIII/IV8Ca}, and {MnIII8Ca2} Complexes with Relevance to Both High-and Low-Valent States of the Oxygen-Evolving Complex. Inorganic Chemistry, 56(17), 10760-10774. doi: 10.1021/acs.inorgchem.7b01740. Lawrence Berkeley National Laboratory: Retrieved from: http://www.escholarship.org/uc/item/8fw5p18f |
| ISSN: | 1520-510X 0020-1669 |
| Popis: | © 2017 American Chemical Society. One-pot reactions between the [Mn3O(O2CPh)6(py)x]+/0triangular precursors and either CaBr2·xH2O or CaCl2·6H2O, in the presence of salicylhydroxamic acid (shaH2), have afforded the heterometallic complexes [MnIII4Ca2(O2CPh)4(shi)4(H2O)3(Me2CO)] (1) and (pyH)[MnII2MnIII4Ca2Cl2(O2CPh)7(shi)4(py)4] (2), respectively, in good yields. Further reactions but using a more flexible synthetic scheme comprising the Mn(NO3)2·4H2O/Ca(NO3)2·4H2O and Mn(O2CPh)2·2H2O/Ca(ClO4)2·4H2O "metal blends" and shaH2, in the presence of external base NEt3, led to the new complexes (NHEt3)2[MnIII4MnIV4Ca(OEt)2(shi)10(EtOH)2] (3) and (NHEt3)4[MnIII8Ca2(CO3)4(shi)8] (4), respectively. In all reported compounds, the anion of the tetradentate (N,O,O,O)-chelating/bridging ligand salicylhydroxime (shi3-), resulting from the in situ metal-ion-assisted amide-iminol tautomerism of shaH2, was found to bridge both Mn and Ca atoms. Complexes 1-4 exhibit a variety of different structures, metal stoichiometries, and Mn oxidation-state descriptions; 1 possesses an overall octahedral metal arrangement, 2 can be described as a Mn4Ca2octahedron bound to an additional Mn2unit, 3 consists of a Mn8"ring" surrounding a CaIIatom, and 4 adopts a rectangular cuboidal motif of eight Mn atoms accommodating two CaIIatoms. Solid-state direct-current magnetic susceptibility studies revealed the presence of predominant antiferromagnetic exchange interactions between the Mn centers, leading to S = 0 spin ground-state values for all complexes. From a bioinorganic chemistry perspective, the reported compounds may demonstrate some relevance to both high-valent scheme (3) and lower-oxidation-level species (1, 2, and 4) of the catalytic cycle of the oxygen-evolving complex. |
| Databáze: | OpenAIRE |
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