13C high resolution nuclear magnetic resonance studies in polycrystalline tetracyanoquinodimethane
13C high resolution nuclear magnetic resonance studies in polycrystalline tetracyanoquinodimethane
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多晶四氰基醌二甲烷的 13C 高分辨率核磁共振研究
DOI：
10.1063/1.462353
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发表时间：
1992
影响因子：
4.4
通讯作者：
M. Almeida
中科院分区：
文献类型：
--
作者：
T. Nunes;A. Vainrub;M. Ribet;F. Rachdi;P. Bernier;M. Almeida
使用不同的多晶样品进行固体中性四氰基对苯醌二甲烷的13 C高分辨率NMR（核磁共振）研究：（i）天然同位素丰度;（ii）15 N同位素富集;（iii）CN基团上选择性富集的13 C同位素;和（iv）CN基团的第一相邻碳上选择性富集的13 C同位素。在CN基团的13 C谱上观察到14N四极效应，得到14N的四极耦合常数：− 3.84 ± 0.12 MHz。发现13 C各向同性化学位移：CN基团为112.6 ppm;直接与这些基团键合的碳为90.8 ppm;质子化碳为132.0和133.2 ppm;醌环上的其他碳为151.7 ppm。通过对CP/MAS谱的图解分析，得到了碎片C-（CN）2中13 C核的化学屏蔽张量、屏蔽各向异性和屏蔽不对称因子的主分量。得到了13C核在CN石墨上的下列值。
13C high resolution NMR (nuclear magnetic resonance) studies of solid neutral tetracyanoquinodimethane are performed using different polycrystalline samples: (i) natural isotopic abundance; (ii) 15N isotope enriched; (iii) 13C isotope selectively enriched on the CN groups; and (iv) 13C isotope selectively enriched on the first neighboring carbons of the CN groups. 14N quadrupole effects are observed on 13C spectra of the CN groups, and the quadrupole coupling constant for 14N is obtained: −3.84±0.12 MHz. The 13C isotropic chemical shifts are found: 112.6 ppm for CN groups; 90.8 ppm for the carbons directly bonded to these groups; 132.0 and 133.2 ppm for protonated carbons; and 151.7 ppm for the other carbons on the quinone ring. The principal components of the chemical shielding tensor, the shielding anisotropy, and the shielding asymmetry factor are also obtained for the 13C nuclei in the fragments C–(CN)2, by graphical analysis of CP/MAS spectra. The following values are obtained for 13C nuclei on CN gr...