Department of Chemistry and Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education , Tsinghua University , Beijing 100084 , China.
Inorg Chem. 2018 May 7;57(9):5499-5506. doi: 10.1021/acs.inorgchem.8b00438. Epub 2018 Apr 24.
The periodic table provides a fundamental protocol for qualitatively classifying and predicting chemical properties based on periodicity. While the periodic law of chemical elements had already been rationalized within the framework of the nonrelativistic description of chemistry with quantum mechanics, this law was later known to be affected significantly by relativity. We here report a systematic theoretical study on the chemical bonding pattern change in the coinage metal dimers (Cu, Ag, Au, Rg) due to the relativistic effect on the superheavy elements. Unlike the lighter congeners basically demonstrating ns- ns bonding character and a 0 ground state, Rg shows unique 6d-6d bonding induced by strong relativity. Because of relativistic spin-orbit (SO) coupling effect in Rg, two nearly degenerate SO states, 0 and 2, exist as candidate of the ground state. This relativity-induced change of bonding mechanism gives rise to various unique alteration of chemical properties compared with the lighter dimers, including higher intrinsic bond energy, force constant, and nuclear shielding. Our work thus provides a rather simple but clear-cut example, where the chemical bonding picture is significantly changed by relativistic effect, demonstrating the modified periodic law in heavy-element chemistry.
周期表为基于周期性定性分类和预测化学性质提供了一个基本的方案。虽然化学元素的周期性规律已经在量子力学的非相对论化学描述框架内得到了合理化，但后来人们知道这个规律受到相对论的显著影响。我们在这里报告了一个关于超重元素相对论效应对金银铜族金属二聚体（Cu、Ag、Au、Rg）化学成键模式变化的系统理论研究。与基本上表现出 ns-ns 成键特征和 0 基态的较轻同系物不同，Rg 由于强相对论诱导出独特的 6d-6d 成键。由于 Rg 中的相对论自旋轨道（SO）耦合效应，两个几乎简并的 SO 态 0 和 2 作为基态的候选态存在。这种成键机制的相对论诱导变化导致了与较轻二聚体相比的各种独特的化学性质的改变，包括更高的内在键能、力常数和核屏蔽。因此，我们的工作提供了一个相当简单但明确的例子，其中化学成键图由于相对论效应而发生了显著变化，展示了重元素化学中修正后的周期性规律。
