Ahmad Saeed, Georgieva Ivelina, Hanif Muhammad, Monim-Ul-Mehboob Muhammad, Munir Shaukat, Sohail Ahsan, Isab Anvarhusein A
Department of Chemistry, College of Sciences and Humanities, Prince Sattam bin Abdulaziz University, Al-Kharj, 11942, Saudi Arabia.
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 11 Acad. G. Bonchev Str., 1113, Sofia, Bulgaria.
J Mol Model. 2019 Mar 8;25(4):90. doi: 10.1007/s00894-019-3970-2.
The structures of non-ionic [Ag(Tu)(CN)] (1) and ionic [Ag(Dmtu)][Ag(CN)] (2) and [Ag(Imt)][Ag(CN)] (3) silver(I) complexes, where Tu = thiourea, Dmtu = N,N'-dimethylthiourea and Imt = imidazoline-2-thione), were modeled by periodic DFT/PAW-PBE calculations; results were in good agreement with experiments. The bonding ability of the thiourea ligands (Tu, Dmtu and Imt) and the rival Ag-C, Ag-S, Ag-N and Ag-Ag bonds were estimated by natural population analysis and natural bonding orbital calculations. The metal-ligand bond strengths were found to decrease in the following order Ag-C > Ag-S > Ag-N, and the main bonding contribution was covalent, donor-acceptor and electrostatic, respectively. The non-ionic [Ag(Tu)(CN)] complex formation [distinguished from the ionic Ag(I) complexes] was explained with the largest bonding capacity of the sulfur donor atom of Tu ligand and the strongest covalent and donor-acceptor Ag-S(Tu) interaction. The infrared (IR) spectra of the experimentally observed structures were reliably interpreted and the IR vibrations, which were sensitive to the ligand coordination to Ag(I) ion and to the weak intra- and intermolecular interactions, were selected with the help of DFT frequency calculations in the solid state. Graphical abstract Non-ionic and ionic complex formation and the different coordination polyhedra around Ag(I) in three AgCN complexes of thioureas were evaluated by natural population analysis, natural bonding orbital, charge density and electron localization function calculations. The predicted largest capacity of sulfur (Tu) for donor-acceptor interaction, the largest bridging sulfur ability for three Ag ions and the strongest covalent and donor-acceptor Ag-S(Tu) interactions in 1 as compared to 2 and 3 explain the formation of a non-ionic complex, i.e., the Ag(CN) anion is missing in 1.
通过周期性密度泛函理论/投影增强波-广义梯度近似（DFT/PAW-PBE）计算对非离子型[Ag(Tu)(CN)]（1）、离子型[Ag(Dmtu)][Ag(CN)]（2）和[Ag(Imt)][Ag(CN)]（3）银（I）配合物的结构进行了模拟，其中Tu = 硫脲，Dmtu = N,N'-二甲基硫脲，Imt = 咪唑啉-2-硫酮；结果与实验结果吻合良好。通过自然布居分析和自然键轨道计算评估了硫脲配体（Tu、Dmtu和Imt）的键合能力以及相互竞争的Ag-C、Ag-S、Ag-N和Ag-Ag键。发现金属-配体键强度按Ag-C＞Ag-S＞Ag-N的顺序降低，且主要的键合贡献分别为共价键、供体-受体键和静电键。非离子型[Ag(Tu)(CN)]配合物的形成（与离子型Ag（I）配合物不同）是由于Tu配体的硫供体原子具有最大的键合能力以及最强的共价和供体-受体Ag-S(Tu)相互作用。对实验观察到的结构的红外（IR）光谱进行了可靠的解释，并借助固态DFT频率计算选择了对配体与Ag（I）离子配位以及弱分子内和分子间相互作用敏感的IR振动。图形摘要 通过自然布居分析、自然键轨道、电荷密度和电子定域函数计算，评估了硫脲的三种AgCN配合物中Ag（I）周围非离子型和离子型配合物的形成以及不同的配位多面体。与2和3相比，1中预测的硫（Tu）供体-受体相互作用的最大能力、三个Ag离子的最大桥连硫能力以及最强的共价和供体-受体Ag-S(Tu)相互作用解释了非离子型配合物的形成，即1中缺少Ag(CN)阴离子。
