Chernyshev Kirill A, Larina Ludmila I, Chirkina Elena A, Krivdin Leonid B
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 1 Favorsky Str, 664033, Irkutsk, Russia.
Magn Reson Chem. 2012 Feb;50(2):120-7. doi: 10.1002/mrc.2854. Epub 2012 Feb 14.
The effects of intramolecular and intermolecular coordination on (31)P nuclear shielding have been investigated in the series of tetracoordinated, pentacoordinated and hexacoordinated N-vinylpyrazoles and intermolecular complexes of N-vinylimidazole and 1-allyl-3,5-dimethylpyrazole with phosphorous pentachloride both experimentally and theoretically. It was shown that either intramolecular or intermolecular coordination involving phosphorous results in a dramatic (31)P nuclear shielding amounting to approximately 150 ppm on changing the phosphorous coordination number by one. A major importance of solvent effects on (31)P nuclear shielding of intramolecular and intermolecular complexes involving N → P coordination bond has been demonstrated. It was found that the zeroth-order regular approximation-gauge-including atomic orbital-B1PW91/DZP method was sufficiently accurate for the calculation of (31)P NMR chemical shifts, provided relativistic corrections are taken into account, the latter being of crucial importance in the description of (31)P nuclear shielding.
通过实验和理论研究了分子内和分子间配位对四配位、五配位和六配位N - 乙烯基吡唑以及N - 乙烯基咪唑和1 - 烯丙基 - 3,5 - 二甲基吡唑与五氯化磷的分子间配合物中(31)P核屏蔽的影响。结果表明，涉及磷的分子内或分子间配位会导致在磷配位数改变一个时，(31)P核屏蔽急剧变化，幅度约为150 ppm。已证明溶剂效应对于涉及N→P配位键的分子内和分子间配合物的(31)P核屏蔽具有重要影响。研究发现，零级正则近似 - 含规范原子轨道 - B1PW91/DZP方法对于(31)P NMR化学位移的计算足够准确，前提是考虑相对论校正，后者对于描述(31)P核屏蔽至关重要。
