Blaakmeer E S Merijn, Franssen Wouter M J, Kentgens Arno P M
Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands; Dutch Polymer Institute (DPI), P.O. Box 902, 5600 AX Eindhoven, The Netherlands.
Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands.
J Magn Reson. 2017 Aug;281:199-208. doi: 10.1016/j.jmr.2017.06.002. Epub 2017 Jun 7.
In this contribution we used solid state Cl (I=3/2) quadrupolar NMR to study a MgCl/2,2-dimethyl-1,3-dimethoxypropane (DMDOMe) adduct that serves as a model system for Ziegler-Natta catalysis. Employing large Radio-Frequency (RF) field strengths we observe three spectral features with strongly varying line widths. The assignment of the spectra is complicated because of the large difference in quadrupolar interactions experienced by the different sites in the system. The satellite transitions (ST) of relatively well-defined bulk Cl sites are partially excited and may overlap with the central transition (CT) resonances of more distorted surface sites. We show that nutation NMR of the ST of I=3/2 spins yields a unique pattern that makes a clear distinction between an extensively broadened central transition and the satellite transitions of a component with a smaller quadrupolar interaction. This allows us to unambiguously unravel the spectra of the MgCl adduct showing that we observe CT and ST of the bulk phase of MgCl-nanoparticles with a C of 4.6MHz together with the CT of surface sites displaying an average C of ∼10MHz.
在本论文中，我们使用固态氯（I = 3/2）四极核磁共振来研究一种氯化镁/2,2 - 二甲基 - 1,3 - 二甲氧基丙烷（DMDOMe）加合物，该加合物作为齐格勒 - 纳塔催化的模型体系。利用大射频（RF）场强，我们观察到三个具有显著不同线宽的光谱特征。由于体系中不同位点所经历的四极相互作用差异很大，光谱的归属变得复杂。相对明确的体相氯位点的卫星跃迁（ST）被部分激发，并且可能与更扭曲的表面位点的中心跃迁（CT）共振重叠。我们表明，I = 3/2自旋的卫星跃迁的章动核磁共振产生了一种独特的模式，该模式能够清楚地区分大幅展宽的中心跃迁和具有较小四极相互作用的组分的卫星跃迁。这使我们能够明确地解析氯化镁加合物的光谱，表明我们观察到了C为4.6MHz的氯化镁纳米颗粒体相的CT和ST，以及平均C约为10MHz的表面位点的CT。
