³⁵Cl/³⁷Cl isotope effects in ¹⁰³Rh NMR of [RhCl_n(H₂O)_{6鈭?span style='font-style: italic'>n}]^{3鈭?span style='font-style: italic'>n} complex anions in hydrochloric acid solution as

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• 作者：Theodor E. Geswindt ; Wilhelmus J. Gerber ; D. Jacobus Brand ; Klaus R. Koch ; ^{krk@sun.ac.za}
• 关键词：103Rh NMR ; 35Cl/37Cl isotope effects in [RhCln(H2O)6&minus ; n]3&minus ; n complexes ; Direct 103Rh NMR speciation ; Isotopologues and isotopomers in NMR
• 刊名：Analytica Chimica Acta
• 出版年：2012
• 期刊代码：2_00032670
• 类别：ch
• 出版时间：12 June, 2012
• 卷：730
• 期：Complete
• 页码：93-98
• 文件大小：633 K

摘要

A detailed analysis of the ³⁵Cl/³⁷Cl isotope effects observed in the 19.11 MHz ¹⁰³Rh NMR resonances of [RhCl_n(H₂O)_6鈭?em>n]^3鈭?em>n complexes (n = 3-6) in acidic solution at 292.1 K, shows that the 鈥榝ine structure鈥?of each ¹⁰³Rh resonance can be understood in terms of the unique isotopologue and in certain instances the isotopomer distribution in each complex. These ³⁵Cl/³⁷Cl isotope effects in the ¹⁰³Rh NMR resonance of the [Rh^35/37Cl₆]^{3鈭?/sup> species manifest only as a result of the statistically expected 35Cl/37Cl isotopologues, whereas for the aquated species such as for example [Rh35/37Cl₅(H₂O)]2鈭?/sup>, cis-[Rh35/37Cl₄(H₂O)₂]鈭?/sup> as well as the mer-[Rh35/37Cl₃(H₂O)₃] complexes, additional fine-structure due to the various possible isotopomers within each class of isotopologues, is visible. Of interest is the possibility of the direct identification of stereoisomers cis-[RhCl₄(H₂O)₂]鈭?/sup>, trans-[RhCl₄(H₂O)₂]鈭?/sup>, fac-[RhCl₃(H₂O)₃] and mer-[RhCl₃(H₂O)₃] based on the 103Rh NMR line shape, other than on the basis of their very similar 未(103Rh) chemical shift. The 103Rh NMR resonance structure thus serves as a novel and unique 鈥楴MR-fingerprint鈥?leading to the unambiguous assignment of [RhCl_n(H₂O)_6鈭?em>n]3鈭?em>n complexes (n = 3-6), without reliance on accurate 未(103Rh) chemical shifts.}