Wang Qian, Pan Sudip, Wu Yan-Bo, Deng Guohai, Bian Jian-Hong, Wang Guanjun, Zhao Lili, Zhou Mingfei, Frenking Gernot
Department of Chemistry, Collaborative Innovation Center of Chemistry for Energy Materials, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, 200433, China.
Institute of Advanced Synthesis, School of Chemistry and Molecular Engineering, Jiangsu National Synergetic Innovation Center for Advanced Materials, Nanjing Tech University, Nanjing, 211816, China.
Angew Chem Int Ed Engl. 2019 Nov 25;58(48):17365-17374. doi: 10.1002/anie.201908572. Epub 2019 Oct 17.
We report the synthesis and spectroscopic identification of the trisbenzene complexes of strontium and barium M(Bz) (M=Sr, Ba) in low-temperature Ne matrix. Both complexes are characterized by a D symmetric structure involving three equivalent η -bound benzene ligands and a closed-shell singlet electronic ground state. The analysis of the electronic structure shows that the complexes exhibit metal-ligand bonds that are typical for transition metal compounds. The chemical bonds can be explained in terms of weak donation from the π MOs of benzene ligands into the vacant (n-1)d AOs of M and strong backdonation from the occupied (n-1)d AO of M into vacant π* MOs of benzene ligands. The metals in these 20-electron complexes have 18 effective valence electrons, and, thus, fulfill the 18-electron rule if only the metal-ligand bonding electrons are counted. The results suggest that the heavier alkaline earth atoms exhibit the full bonding scenario of transition metals.
我们报道了在低温氖基质中锶和钡的三苯配合物M(Bz)₃（M = Sr，Ba）的合成及光谱鉴定。两种配合物的特征均为具有D₃对称结构，包含三个等效的η⁶-键合苯配体和闭壳层单重态电子基态。电子结构分析表明，这些配合物呈现出过渡金属化合物典型的金属-配体键。化学键可以通过苯配体的π分子轨道向M的空(n - 1)d原子轨道的弱电子给予以及M占据的(n - 1)d原子轨道向苯配体的空π*分子轨道的强反馈来解释。这些20电子配合物中的金属具有18个有效价电子，因此，如果仅计算金属-配体成键电子，则符合18电子规则。结果表明，较重的碱土原子呈现出过渡金属的完整成键情况。
