Perfluoroalkyl Cobaloximes: Preparation Using Hypervalent Iodine Reagents, Molecular Structures, Thermal and Photochemical Reactivity
Perfluoroalkyl Cobaloximes: Preparation Using Hypervalent Iodine Reagents, Molecular Structures, Thermal and Photochemical Reactivity
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全氟烷基钴肟：使用高价碘试剂制备、分子结构、热和光化学反应性
DOI：
10.1021/acs.organomet.7b00892
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发表时间：
2018
期刊：
影响因子：
2.8
通讯作者：
A. Togni
中科院分区：
文献类型：
--
作者：
P. Liebing;F. Oehler;M. Wagner;P. F. Tripet;A. Togni
用全氟烷基碘试剂处理钴肟（II），[Co（Hdmg）2（L）2]（Hdmg =二甲基乙二醛，L =中性配体），导致形成全氟烷基钴肟（III），[CoRF（Hdmg）2（L）]（RF= CF 3，C2 F5，n-C3 F7，CF 2CF 2 Ph; L = Py，NH 3，MeNH 2，PhNH 2，MeOH）。合成方案可以显著简化为从乙酸钴（II）-四水合物开始的一锅法。通过核磁共振、红外光谱、紫外维斯光谱和单晶X射线衍射对产物进行了表征，并研究了其热反应性和光化学反应性。根据晶体中Co-L的距离，RF配体的反作用大小为C_2F_5-n-C_3F_7-<CF_2CF_2Ph-n-CF_3-<CH_3-。的配合物的热分解是不同的非氟化类似物，可能包括作为初始步骤的Hdmg-配体的全氟烷基化。在CF 3配合物中，Co-C键非常耐光解，但配体L在暴露于蓝光时容易被MeOH交换。在具有较长RF链的配合物中，Co-C键更容易断裂，并且产物分布强烈地依赖于O2的存在。因此，烷烃RFH是排除O2的主要产物，而氟化甲酯和HF在暴露于空气的甲醇溶液中形成。
Treatment of cobaloximes(II), [Co(Hdmg)2(L)2] (Hdmg = dimethylglyoximate, L = neutral ligand), with perfluoroalkyl iodane reagents leads to the formation of perfluoroalkyl cobaloximes(III), [CoRF(Hdmg)2(L)] (RF= CF3, C2F5,n-C3F7, CF2CF2Ph; L = Py, NH3, MeNH2, PhNH2, MeOH). The synthetic protocol can be significantly simplified to a one-pot procedure starting from cobalt(II) acetate–tetrahydrate. The products have been fully characterized by NMR, IR, and UV/vis spectroscopy as well as single-crystal X-ray diffraction, and the thermal and photochemical reactivity has been studied. According to the Co–L distances in the crystal, thetransinfluence of the RF–ligands can be rated as C2F5–≈n-C3F7–< CF2CF2Ph–≈ CF3–< CH3–. The thermal decomposition of the complexes is different from that of nonfluorinated analogues, probably including perfluoroalkylation of an Hdmg–ligand as the initial step. In the CF3complexes, the Co–C bond is very resistant against photolysis, but the ligand L is readily exchanged by MeOH upon exposure to blue light. In the complexes with longer RFchains, the Co–C bond is more readily cleaved, and the product distribution depends strongly on the presence of O2. Thus, the alkane RFH is the main product under exclusion of O2, while a fluorinated methyl ester and HF are formed in a methanol solution exposed to air.