Cao Guo-Jin
Institute of Molecular Science, Shanxi University, Taiyuan, 030006, China.
Sci Rep. 2017 Nov 2;7(1):14896. doi: 10.1038/s41598-017-14259-2.
Dinuclear metal-mediated homo base pairs are interesting clusters with highly symmetric structures and significant stabilities. The geometric and electronic structures of GM (G = Guanine, M = Cu, Ag or Au) cluster ions were studied with quantum chemical calculations. The lowest-energy isomers of GM cluster ions have C symmetries with an approximately antiparallel alignment of two sets of N-M∙∙∙O groups being formed in the planar structures. The M-M distances are shorter than the sum of van der Waals radii of corresponding two homo coinage metal atoms, showing that metallophilic interactions significantly exist in these complexes. They have the large HOMO-LUMO gaps of about 5.80 eV at the DFT level and the bond dissociation energies of more than 5.60 eV at the DFT/B3LYP level, indicating that these cluster dications are highly stable. The second lowest-energy isomers stabilized by an approximately parallel alignment of one set of O-M-O group and one set of N-M-N group are found to be close to the lowest-energy isomers in energy. The barrier between the two isomers of GM cluster ions is significantly large, also showing that these lowest-energy isomers are very stable.
双核金属介导的同碱基对是具有高度对称结构和显著稳定性的有趣簇合物。利用量子化学计算研究了GM（G = 鸟嘌呤，M = 铜、银或金）簇离子的几何和电子结构。GM簇离子的最低能量异构体具有C对称性，在平面结构中形成两组N-M∙∙∙O基团的近似反平行排列。M-M距离短于相应两个同价金属原子的范德华半径之和，表明这些配合物中显著存在亲金属相互作用。在DFT水平下，它们具有约5.80 eV的大HOMO-LUMO能隙，在DFT/B3LYP水平下具有超过5.60 eV的键解离能，表明这些簇二价阳离子高度稳定。通过一组O-M-O基团和一组N-M-N基团的近似平行排列稳定的第二低能量异构体在能量上接近最低能量异构体。GM簇离子的两种异构体之间的势垒非常大，这也表明这些最低能量异构体非常稳定。
