Gd2@C79N: isolation, characterization, and monoadduct formation of a very stable heterofullerene with a magnetic spin state of S = 15/2.
Gd2@C79N: isolation, characterization, and monoadduct formation of a very stable heterofullerene with a magnetic spin state of S = 15/2.
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DOI：
10.1021/ja202011u
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发表时间：
2011-06-29
影响因子：
15
通讯作者：
Dorn, Harry C.
中科院分区：
文献类型：
--
作者：
Fu, Wujun;Zhang, Jianyuan;Fuhrer, Tim;Champion, Hunter;Furukawa, Ko;Kato, Tatsuhisa;Mahaney, James E.;Burke, Brian G.;Williams, Keith A.;Walker, Kenneth;Dixon, Caitlyn;Ge, Jiechao;Shu, Chunying;Harich, Kim;Dorn, Harry C.
与早期报道的异富勒烯 Y2@C79N 相比，二金属内嵌杂富勒烯 (EHF) Gd2@C79N 的制备和分离收率相对较高。计算 (DFT)、化学反应性、拉曼和电化学研究均表明，具有异富勒烯笼 (C79N)5- 的纯化 Gd2@C79N 具有与其他更知名的等电子金属富勒烯 (C80)6- 笼物种（例如 Gd3N@C80）相当的稳定性。这些结果描述了一种异常稳定的顺磁分子，其化学反应性低，不成对的电子自旋密度位于内部双原子钆簇上，而不是在异富勒烯笼上。 EPR研究证实Gd2@C79N的自旋态具有半整数自旋量子数S = 15/2的特征。富勒烯笼的 N 原子上的自旋 (S = 1/2) 和两个封装钆的两个八位组自旋 (S = 7/2) 以铁磁方式相互耦合，具有小的零场分裂参数 D。因为 Gd2@C79N 的中心线是由于半整数自旋量子数 S = 15/2 的克莱默双峰，所以这 相对尖锐的线突出，线的各向异性性质较弱。有趣的是，与大多数 Gd3+ 离子环境相比，即使在室温下的甲苯溶液中也可以观察到中心 EPR 线 (g=1.978)。最后，我们报告了第一个 EHF 衍生物，即 Gd2@C79N 的溴丙二酸二乙酯单加合物，是通过改进的 Bingel-Hirsch 反应制备和分离的。
The dimetallic endohedral heterofullerene (EHF), Gd2@C79N, was prepared and isolated in a relatively high yield when compared with the earlier reported heterofullerene, Y2@C79N. Computational (DFT), chemical reactivity, Raman, and electrochemical studies all suggest that the purified Gd2@C79N, with the heterofullerene cage, (C79N)5- has comparable stability with other better known isoelectronic metallofullerene (C80)6- cage species (e.g., Gd3N@C80). These results describe an exceptionally stable paramagnetic molecule with low chemical reactivity with the unpaired electron spin density localized on the internal diatomic gadolinium cluster and not on the heterofullerene cage. EPR studies confirm that the spin state of Gd2@C79N is characterized by a half-integer spin quantum number of S = 15/2. The spin (S = 1/2) on the N atom of the fullerene cage and two octet spins (S = 7/2) of two encapsulated gadoliniums are coupled with each other in a ferromagnetic manner with a small zero-field splitting parameter D. Because the central line of Gd2@C79N is due to the Kramer's doublet with a half-integer spin quantum number of S = 15/2, this relatively sharp line is prominent and the anisotropic nature of the line is weak. Interestingly, in contrast with most Gd3+ ion environments, the central EPR line (g=1.978) is observable even at room temperature in a toluene solution. Finally, we report the first EHF derivative, a diethyl bromomalonate monoadduct of Gd2@C79N, was prepared and isolated via a modified Bingel-Hirsch reaction.
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