Hybridized valence electrons of 4f^0-145d^0-16s²: the chemical bonding nature of rare earth elements

薛冬峰，孙丛婷，陈小艳

State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied Chemistry Chinese Academy of Sciences

摘 要：The chemical bonding nature of rare earth（RE） elements can be studied by a quantitative analysis of electron domain of an atom. The outer electrons of RE elements are within the valence shell 4f^0-145d^0-16s², which are involved in all chemical bonding features. We in this work found that the chemical bonding characteristics of 4f electrons are a kind of hybridizations, and classified them into three types of chemical bonding of 4f^0-145d^0-16s², furthermore, the coordination number ranging from 2 to 16 could thus be determined. We selected Y（NO₃）₃, La（NO₃）₃, Ce（NO₃）₃, YCl₃, LaCl₃, and CeCl₃ as examples to in-situ observe their IR spectra of chemical bonding behaviors of Y³⁺, La³⁺ and Ce³⁺ cations, which could show different chemical bonding modes of 4f and 5d electrons. In the present study, we obtained the direct criterion to confirm whether 4f electrons can participate in chemical bonding, that is, only when the coordination number of RE cations is larger than 9.

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