2) coupling constant 偶合常数 1. The coupling constants between 19 F and 1H/ 13 C were determined accurately. 用1 H ,1 3CNMR和多种二维核磁共振谱表征了本系列化合物的结构 ,完成了1 H和1 3CNMR谱带的归属 ,测定了氟原子对各质子和碳原子的偶合常数 ,探讨了影响偶合常数大小的因素。 2. The...
aluminum, AlThe study experimentally confirms estimated and calculated values of the quadrupole coupling constant for (Al(H 2 O) 6 ) 3+ and demonstrates that 27 Al NMR can be used as a probe for the ligand field asymmetry in Al(III) complexes....
(TRAPDOR) NMR introduced by Grey and Vega100was applied to distinguish the protons that are coupled or not with27Al and determine thequadrupolecoupling constant of the “invisible aluminium” in dehydratedzeoliteHY.101,102In addition,27AlMQ MASNMR has been used to detect the frameworkaluminium...
In several of these complexes, the JC–H NMR spin–spin coupling constant of the α-alkylidene C–H bond is low. This has been attributed to a weakening of the C–H bond due to the presence of an α-C–H agostic interaction, i.e., an intramolecular interaction between the C–H ...
本帖最后由 liyuanhe211 于 2015-11-20 22:59 编辑 打开看,J-J coupling constant都以两两原子间...
Analysis of the signal reduction as a function of the irradiation-frequency offset allows a determination of the quadrupole coupling constant of the Al-27 nuclei as well as an estimation of the asymmetry parameter and the geometry of the Al-H vector. This technique provides a means of ...
Dihedral angle and bond angle dependence of vicinal proton-fluorine spin-spin coupling From an analysis of the nmr spectra of compounds of fixed and known stereochemistry the vicinal proton-fluorine coupling constant has been found to be a fu... KL Williamson,YF Li,FH Hall,... - 《Journal ...
NMR spin-spin coupling constants are calculated by means of the extended H眉ckel molecular orbital theory (EHMO). The contributions to the coupling constant from orbital, spin-dipolar, and Fermi-contact interactions are included. By use ... FAAM De Leeuw,CAG Haasnoot,C Altona - 《Journal of...
The INEPT (insensitive nuclei enhanced by polarization transfer) experiment is similar to the DEPT experiment, except that it uses an evolution period to produce the appropriate condition for spectral selection that depends critically on the size of the coupling constant. The technique is therefore som...
From the NMR data, the dimerization constant for 1H-pyrrolo[2,3-b]pyridine (1) has been determined to be 18.9 ± 10.3 mol 1−1 〈81JPC3181〉. 7.06.3.1.1.(ii) Furopyridines Proton NMR data for some parent furopyridines and a variety of derivatives are listed in Table 19. Some ...