Ion-Pairing of Phosphonium Salts in Solution: CH⋅⋅⋅Halogen and CH⋅⋅⋅π Hydrogen Bonds
作者:Johannes Ammer、Christoph Nolte、Konstantin Karaghiosoff、Sebastian Thallmair、Peter Mayer、Regina de Vivie-Riedle、Herbert Mayr
DOI:10.1002/chem.201204561
日期:2013.10.18
concentration dependence of the 1H NMR chemical shifts allowed us to determine the dissociation constants of the phosphonium salts in CD2Cl2 solution. The cation–anion interactions increase with the acidity of the C(α)H protons and the basicity of the anion. The existence of CH⋅⋅⋅X− hydrogen bonds between the cations and anions is confirmed by quantum chemical calculations of the ion pair structures, as well
该1角作为C 1 H NMR化学位移(α) ħ芳甲基三苯基鏻离子,CD的质子2氯2溶液强烈地依赖于对阴离子X - 。对于二苯甲基衍生物pH值值2 CH PPH 3 + X - ,例如,范围从δ ħ = 8.25(X - =氯- )在6.23(X - = BF 4 - ),以5.72 ppm的(X - = BPH 4 −)。类似的,尽管观察到抗衡离子诱导的变化较弱。所有芳基的邻质子。浓度依赖性的NMR研究显示,大位移从质子的由阴离子去屏蔽,它在顺序减少导致氯- >溴- »BF 4 - >的SbF 6 - 。对于体积较小的衍生物的PhCH 2 PPH 3 + X - ,我们还求c ℃之间H⋅⋅⋅Ph相互作用(α) H和苯基的BPH的4 -阴离子,其导致高磁场NMR的化学位移C(α)H质子 这些相互作用也可以在(p -CF 3 -C 6 ħ 4)CH 2 PPH 3 +