作者:Robert T. Hart、Josef W. Zwanziger
DOI:10.1111/j.1551-2916.2005.00429.x
日期:——
The synthesis of 17O‐enriched α‐tellurite (α‐TeO2) is described. TeO2 is obtained stochiometrically by the reaction of tellurium isopropoxide with 17O‐enriched H2O. The reaction is mild and simple and opens the field of tellurite‐based ceramics to 17O nuclear magnetic resonance spectroscopy. We also report the first 17O nuclear magnetic resonance spectra of α‐TeO2 and Na2TeO3. Their isotropic chemical shifts, δiso, are 180 ppm and 158 ppm, respectively, and their quadrupolar coupling parameters are CQ=7.48 MHz and η=0.43 for α‐TeO2, and CQ=6.63 MHz and η=0.33. By using extended Hückel tight binding calculations, we interpret the chemical shifts of tetravalent inorganic oxide network formers (SiO2, GeO2, and TeO2) in terms of the local paramagnetic shielding effect. We also show that this is the predominant effect in determining the chemical shifts of non‐bridging oxide sites in this type of network.
富氧-17 α-氧化碲(α-TeO2)的合成被详细描述:通过富氧-17水与碲异丙醇的反应,以化学计量比获得TeO2。该反应条件温和且简单,为基于氧化碲的陶瓷材料打开了通向富氧-17核磁共振光谱研究的大门。我们首次报告了α-TeO2和Na2TeO3的富氧-17核磁共振光谱。它们的各向同性化学位移δ_iso分别为180 ppm和158 ppm,且四极耦合参数分别为:α-TeO2的C_Q=7.48 MHz、η=0.43;而Na2TeO3的C_Q=6.63 MHz、η=0.33。通过扩展Hückel紧束缚计算,我们用局部顺磁性屏蔽效应解释了四价无机氧化物网状结构起始物(SiO2, GeO2, TeO2)的化学位移。我们还表明:这一效应是决定此类网络中非桥接氧化物位点的化学位移的主要因素。