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Perfluoroalkyl Cobaloximes: Preparation Using Hypervalent Iodine Reagents, Molecular Structures, Thermal and Photochemical Reactivity
Organometallics ( IF 2.5 ) Pub Date : 2018-02-08 00:00:00 , DOI: 10.1021/acs.organomet.7b00892
Phil Liebing 1 , Florian Oehler 2 , Mona Wagner 1 , Pascal F. Tripet 1 , Antonio Togni 1
Affiliation  

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, the trans influence of the RF ligands can be rated as C2F5n-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 CF3 complexes, 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 RF chains, 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.

中文翻译:

全氟烷基钴肟类:使用高价碘试剂的制备,分子结构,热和光化学反应性

用全氟烷基碘试剂处理钴酸肟(II),[Co(Hdmg)2(L)2 ](Hdmg =二甲基乙二肟酸酯,L =中性配体)导致形成全氟烷基钴肟(III),[CoR F(Hdmg)2(L)](R F = CF 3,C 2 F 5n -C 3 F 7,CF 2 CF 2 Ph; L = Py,NH 3,MeNH 2,PhNH 2,MeOH)。从醋酸钴(II)四水合物开始,合成方案可以显着简化为一锅法。产品已通过NMR,IR和UV / Vis光谱以及单晶X射线衍射进行了充分表征,并对热和光化学反应性进行了研究。根据在晶体中钴-L距离处,反式中的R影响˚F -配体可以评价为C 2 ˚F 5 -Ñ -C 3 ˚F 7 - <CF 2 CF 2博士- ≈CF 3 - <CH 3 。配合物的热分解与非氟化类似物的热分解不同,第一步可能包括将Hdmg 配体进行全氟烷基化。在CF 3络合物中,Co-C键非常抗光解,但配体L在暴露于蓝光下很容易被MeOH交换。在具有较长R F链的配合物中,Co-C键更容易断裂,并且产物的分布在很大程度上取决于O 2的存在。因此,烷烃R F H是排除O 2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。
更新日期:2018-02-09
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