Theoretical Study of Nonclassical Platinum Complexes Bonding to Purine Bases: How the Long-lived Monofunctional Adducts Can Be in Existence?  

作　　者：常贯儒 周立新 陈动 

机构地区：[1]Department of Chemistry, Jinan University, Guangzhou, Guangdong 510632, China

出　　处：《Chinese Journal of Structural Chemistry》2006年第4期407-416,共10页结构化学（英文）

基　　金：This work was supported by the Science Foundation of Jinan University (639)

摘　　要：The B3LYP/6-31G^＊ level of theory was used for the optimization of nonclassical platinum drugs with planar aromatic heterocycle ligands in addition to their monoaqua species, diaqua species and monofunctional adducts. Single point calculations were performed on optimized geometries using the MP2/6-31G^＊＊ method, and the Lanl2dz pseudo potential for the Pt atom remained constant in all calculations. It can be easily seen that the trans effect can influence both geometrical structures and bond dissociating energies （BDEs）. On the basis of our calculation, we get that the long-lived monofunctional adducts with chloride ligand may be in existence, because they possessed higher stability energies, easily dissociated chloride compared with the monoaqua species dissociating chloride and that replacement of the first chloride by bases became exothermic in solution. Our calculated results also demonstrate that the strongest H-bonds appear in the complexes of q-wG and t-wG using different methods. In comparison with adenine complexes, the corresponding guanine complexes possess larger interaction energies as well as higher stability energies either corrected by basis set superposition error （bsse） of Boys-Bernardi counterpoise method or uncorrected both in gas phase and in solution with one exception that the stability energy of q-CIA complex in solution is larger than that of q,CIG complex. Finally, the nature of bond was analyzed in terms of partial charges distribution based on NBO population.The B3LYP/6-31G^＊ level of theory was used for the optimization of nonclassical platinum drugs with planar aromatic heterocycle ligands in addition to their monoaqua species, diaqua species and monofunctional adducts. Single point calculations were performed on optimized geometries using the MP2/6-31G^＊＊ method, and the Lanl2dz pseudo potential for the Pt atom remained constant in all calculations. It can be easily seen that the trans effect can influence both geometrical structures and bond dissociating energies （BDEs）. On the basis of our calculation, we get that the long-lived monofunctional adducts with chloride ligand may be in existence, because they possessed higher stability energies, easily dissociated chloride compared with the monoaqua species dissociating chloride and that replacement of the first chloride by bases became exothermic in solution. Our calculated results also demonstrate that the strongest H-bonds appear in the complexes of q-wG and t-wG using different methods. In comparison with adenine complexes, the corresponding guanine complexes possess larger interaction energies as well as higher stability energies either corrected by basis set superposition error （bsse） of Boys-Bernardi counterpoise method or uncorrected both in gas phase and in solution with one exception that the stability energy of q-CIA complex in solution is larger than that of q,CIG complex. Finally, the nature of bond was analyzed in terms of partial charges distribution based on NBO population.

关 键 词：long-lived monofunctional adducts diaqua species intrastrand cross-Hnk DFT MP2 

分 类 号：O611.3[理学—无机化学]