A Localized Molecular Orbital Study of the Halogen Substitution Effect on 103Rh NMR Shielding in [Cp*RhX2]2, Where X = Cl, Br, or I

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• 作者：Irina V. Mirzaeva ; Dmitry A. Mainichev ; Svetlana G. Kozlova
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：March 24, 2016
• 年：2016
• 卷：120
• 期：11
• 页码：1944-1949
• 全文大小：303K
• ISSN：1520-5215

文摘

¹⁰³Rh NMR parameters and the bonding structure of three complexes of [Cp*RhX₂]₂, where X = Cl, Br, or I, have been studied with the help of natural bond orbitals (NBOs) and natural localized molecular orbitals (NLMOs). The complexes of [Cp*RhX₂]₂, where X = Cl, Br, or I, have similar bonding structures, with the major difference being in the degree of covalency of the Rh–X bonds. The decomposition of ¹⁰³Rh NMR shielding into diamagnetic, paramagnetic, and spin–orbit terms shows that normal halogen dependence (NHD) of the ¹⁰³Rh NMR shift is defined mostly by the paramagnetic term, with the spin–orbit term being significantly smaller. The decomposition of ¹⁰³Rh shielding into spin-free NBO and NLMO contributions shows that ¹⁰³Rh shielding is dominated by Rh d-orbital deshielding contributions. We explain the NHD of the ¹⁰³Rh NMR shift with the increase in the energies of the virtual antibonding Rh–X orbitals along the X = Cl, Br, and I series.