请教高手

jeffzhao

    我是个核磁新手，最近在解析化合物构型的时候遇到一个棘手问题，需要对1JCH碳氢一键耦合常数进行测定与理论值比较，请教核磁高手们，常用的测量一键耦合常数的方法有哪些呢？急！！！

celan

Stereochemical dependence of NMR geminal spin-spin coupling constants.
Magnetic resonance in chemistry : MRC 2009;47(2):113-20.
In this work it was sought to explore the versatility of geminal spin-spin coupling constants, (2)J(XY) SSCCs, as probes for stereochemical studies. A set of compounds, where their experimental (2)J(XY) SSCCs through the X-C-Y molecular fragment are predicted to be sensitive to hyperconjugative interactions involving either bonding or antibonding orbitals containing the C carbon atom ('coupling pathway'), were analyzed. SSCC calculations were performed for some selected examples using the second order polarization propagator approximation (SOPPA) method or within the DFT-B3LYP framework. Hyperconjugative interactions were calculated within the Natural Bond Orbital (NBO) approach. Results are condensed in two qualitative rules: Rule I(M)-hyperconjugative interactions transferring charge into the coupling pathway yield a positive increase to the Fermi contact (FC), contribution to (2)K(XY) reduced spin-spin coupling constants (RSSCC), and Rule II(M)-hyperconjugative interactions transferring charge from the coupling pathway yield a negative increase to the FC contribution to (2)K(XY) RSSCC

celan

Density functionals for calculating NMR ¹J_CH coupling constants in electron-rich systems

 

b0 n5 P3 q. b4 t. Q% \

/ z/ p: {% g& S& B7 o D/ W2 ~1 b1 j: W0 p( k% k: k1 U4 H0 }$ S) B4 z+ ~3 b8 Z* V% p0 p* j/ s1 ^

& W5 P3 B& h) {' a0 S( O Chemical Physics Letters Volume 454, Issues 1-3, 10 March 2008, Pages 129-132

jeffzhao

谢谢指教！！！