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首页> 外文期刊>Chemistry: A European journal >Synthesis,Characterization,and Theoretical Study of Stable Isomers of C_(70)(CF_3)_n(n=2,4,6,8,10)
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Synthesis,Characterization,and Theoretical Study of Stable Isomers of C_(70)(CF_3)_n(n=2,4,6,8,10)

机译：C_（70）（CF_3）_n（n = 2,4,6,8,10）的稳定异构体的合成，表征和理论研究

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Reaction of C_(70)with tenequivalents of silver(I)trifluoroacetate at 320-340 deg C followed by fractional sublimation at 420-540 deg C and HPLC processing led to the isolation of a single abundant isomer of C_(70)(CF_3)_n for n=2,4,6,and 10,and two abundant isomers of C_(70)(CF_3)_8.These six compounds were characterized by using matrix-assisted laser desorption ionization(MALDI)mass spectrometry,2D-COSY and/or 1D ~(19)F NMR spectroscopy,and quantum-chemical calculations at the density functional theory(DFT)level.Some were also characterized by Raman spectroscopy.The addition patterns for the isolated compounds were unambiguously found to be C_1-7,24-C_(70)(CF_3)_2,C_1-7,24,44,47-C_(70)(CF_3)_4,C_2-1,4,11,19,31,41-C_(70)(CF_3)_6,C_s-1,4,11,19,31,41,51,64-C_(70)(CF_3)_8, C_2-1,4,11,19,31,41,51,60-C_(70)(CF_3)_8,and Cr 1,4,10,19,25,41,49,60,66,69-C_(70)(CF_3)_(10)(IUPAC numbering).Except for the last compound,which is identical to the recently reported,crystallographi-cally characterized C_(70)(CF_3)_(10)derivative prepared by a different synthetic route,these compounds have not previously been shown to have the indicated addition patterns.The largest relative yield under an optimized set of reaction conditions was for the C_s isomer of C_(70)(CF_3)_8(ca.30 mol% of the sublimed mixture of products based on HPLC integration).The results demonstrate that thermally stable C_(70)(CF_3)_n isomers tend to have their CF_3 groups arranged on isolated para-C_6(CF_3)_2 hexagons and/or on a ribbon of edge-sharing meta-and/or para-C_6(CF_3)_2 hexagons.For C_s-and C_2-C_(70)(CF_3)_8 and for C_2-C_(70)(CF_3)__6,the ribbons straddle the C_(70)equatorial befor C_1-C_(70)-(CF_3)_4,the para-meta-para ribbon includes three polar hexagons;for C_1-7,24-C_(70)(CF_3)_2,the para-C_6(CF_3)_2 hexagon includes one of the carbon atoms on a C_(70)polar pentagon.The 10.3-16.2 Hz ~7J_(F,F)NMR coupling constants for the end-of-ribbon CF_3 groups,which are always para to their nearest-neighbor CF_3 group,are consistent with through-space Fermi-contact interactions between the fluorine atoms of proximate,rapidly rotating CF_3 groups.
机译：C_（70）与十分当量的三氟乙酸银（I）在320-340℃下反应，然后在420-540℃进行部分升华，并进行HPLC处理，从而分离出C_（70）（CF_3）的单一丰富异构体_n代表n = 2、4、6和10，以及C_（70）（CF_3）_8的两个丰富的异构体。这六个化合物通过基质辅助激光解吸电离（MALDI）质谱，2D-COSY和/或1D〜（19）F NMR光谱，以及在密度泛函理论（DFT）级别上的量子化学计算。拉曼光谱还对其中一些进行了表征。明确地发现分离出的化合物的加成模式为C_1-7， 24-C_（70）（CF_3）_2，C_1-7,24,44,47-C_（70）（CF_3）_4，C_2-1,4,11,19,31,41-C_（70）（CF_3 ）_6，C_s-1,4,11,19,31,41,51,64-C_（70）（CF_3）_8，C_2-1,4,11,19,31,41,51,60-C_（ 70）（CF_3）_8和Cr 1,4,10,19,25,41,49,60,66,69-C_（70）（CF_3）_（10）（IUPAC编号）。最后一个化合物除外与最近报道的晶体学特征相同d通过不同的合成路线制备的C_（70）（CF_3）_（10）衍生物，以前并未显示这些化合物具有所示的加成模式。在优化的一组反应条件下，最大的相对产率是C_s异构体C_（70）（CF_3）_8（基于HPLC积分的升华产物混合物的30 mol％）结果表明，热稳定的C_（70）（CF_3）_n异构体倾向于将CF_3基团排列在隔离的对等C_6（CF_3）_2六边形和/或在边共享元和/或对等C_6（CF_3）_2六边形的功能区上。对于C_s-和C_2-C_（70）（CF_3）_8以及对于C_2 -C_（70）（CF_3）__ 6，色带横跨C_（70）赤道带;对于C_1-C_（70）-（CF_3）_4，对位-对位带包括三个极性六边形;对于C_1-7 ，24-C_（70）（CF_3）_2，对-C_6（CF_3）_2六边形在C_（70）极性五边形上包含一个碳原子.10.3-16.2 Hz〜7J_（F，F）NMR耦合功能区末尾CF_3组的常数，它们始终与其最近邻CF相关_3基团与快速旋转的CF_3基团的氟原子之间的空间费米接触相互作用一致。

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