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异三金属镧系元素(III)/锰(III) 12-冠-4配合物的¹H NMR顺磁特征解析

Elucidation of H NMR Paramagnetic Features of Heterotrimetallic Lanthanide(III)/Manganese(III) 12-MC-4 Complexes.

作者信息

Atzeri Corrado, Marzaroli Vittoria, Quaretti Martina, Travis Jordan R, Di Bari Lorenzo, Zaleski Curtis M, Tegoni Matteo

机构信息

Department of Chemistry, Life Sciences, and Environmental Sustainability, University of Parma , Parco Area delle Scienze 11A, 43124 Parma, Italy.

Department of Chemistry and Biochemistry, Shippensburg University , Shippensburg, Pennsylvania 17257-2200, United States.

出版信息

Inorg Chem. 2017 Jul 17;56(14):8257-8269. doi: 10.1021/acs.inorgchem.7b00970. Epub 2017 Jul 5.

Abstract

The paramagnetic one-dimensional H NMR spectra of twelve LnNa(OAc)[12-MC-4] complexes, where Ln is Pr-Yb (except Pm) and Y, are reported. Their solid-state isostructural nature is confirmed in methanol-d solution, as a similar pattern in the H NMR spectra is observed along the series. Notably, a relatively well-resolved spectrum is reported for the Gd complex. The chemical shift data are analyzed using the "all lanthanides" method, and the Fermi contact and pseudo-contact contributions are calculated for the lanthanide-induced shift (LIS). For the Tb-Yb complexes, the pseudo-contact contributions are typically 1 order of magnitude higher than the Fermi contact contributions; however, for the Gd complex, the Fermi contact is the main contribution to the paramagnetic chemical shift. For the methyl protons of the axial acetate (OAc) ligands, the LIS is opposite in sign, with respect to that of the aromatic salicylhydroximate (shi) protons, because of structural rearrangements that occur upon dissociation of the Na cation in solution. The calculated crystal field parameters (B) for the Tb (360 cm), Dy (250 cm), Ho (380 cm), Er (410 cm), Tm (620 cm), and Yb (380 cm) complexes are not constant, likely as a consequence of the inaccuracy of the Bleaney's constants and, to a smaller extent, the small structural changes that occur in solution. Overall, the metallacrown scaffold retains structural integrity and similarity in solution for the entire series; however, small structural features, which do not affect the overall similarity, do likely occur.

摘要

报道了12种LnNa(OAc)[12-MC-4]配合物的顺磁一维氢核磁共振谱,其中Ln为Pr - Yb(钷除外)和Y。在氘代甲醇溶液中证实了它们的固态同构性质,因为在该系列中观察到氢核磁共振谱有相似的模式。值得注意的是,报道了钆配合物的相对分辨率较好的谱图。使用“所有镧系元素”方法分析化学位移数据,并计算镧系元素诱导位移(LIS)的费米接触贡献和赝接触贡献。对于铽 - 镱配合物,赝接触贡献通常比费米接触贡献高1个数量级;然而,对于钆配合物,费米接触是顺磁化学位移的主要贡献。对于轴向乙酸根(OAc)配体的甲基质子,由于溶液中钠离子解离时发生的结构重排,LIS的符号与芳基水杨羟肟酸(shi)质子的相反。计算得到的铽(360 cm⁻¹)、镝(250 cm⁻¹)、钬(380 cm⁻¹)、铒(410 cm⁻¹)、铥(620 cm⁻¹)和镱(380 cm⁻¹)配合物的晶体场参数(B)不是恒定的,这可能是由于布莱尼常数不准确以及在较小程度上溶液中发生的小结构变化所致。总体而言,金属冠支架在整个系列的溶液中保持结构完整性和相似性;然而,确实可能存在不影响整体相似性的小结构特征。

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