Potential Energy Surfaces for Ligand Exchange Reactions of Square Planar Diamagnetic PtY2L2 Complexes:Hydrogen Bond (PtY2L2…L') versus Apical (Y2L2Pt…L') Interaction

• Published in: Bulletin of the Korean Chemical Society Vol. 27; no. 9; pp. 1405 - 1417
• Main Authors: 박종근, Bong Gon Kim
• Format: Journal Article
• Language: English
• Published: 대한화학회 20.09.2006
• Subjects: 화학
• ISSN: 0253-2964; 1229-5949
• DOI: 10.5012/bkcs.2006.27.9.1405

The geometrical structures, potential energysurfaces, and energetics for the ligand exchange reactions of tetracoordinated platinum (PtY2L2 : Y, L=Cl-, OH-, OH2, NH3) complexes in the ligand-solvent interaction systems were investigated using the ab initio Hartree-Fock (HF)and Density Functional Theory (DFT) methods. The potential energy surfaces for the ligand exchange reactions used for the conversionsof (PtCl4 + H2O) to [PtCl3(H2O) + Cl-] and [Pt(NH3)2Cl2 + H2O] to [Pt(NH3)2Cl(H2O) + Cl-] were investigated in detail. For these two exchange reactions, the transition states ([PtY2L2…L']‡) correspond to complexes such as (PtCl4갤H2O)‡ and [Pt(NH3)2Cl2갤H2O]‡, respectively. In the transition state, ([PtCl4갤H2O]‡ and [Pt(NH3)2Cl2갤H2O]‡) have a kind of 6-membered (Pt-Cl°¶HOH°¶Cl) and (Pt-OH°¶Cl°¶HN)interactions, respectively,wherein a central Pt(II) metal directly combines with a leaving Cl- and an entering H2O. Simultaneously, the entering H2O interactswith a leaving Cl-. No vertical one metal-ligand interactions ([PtY2L2갤L']‡) are found at the axial positions of the square planar (PtY2L2) complexes, which were formed via a vertically associative mechanism leading to D3h or C2v-transition state symmetry. The geometrical structure variations, molecular orbital variations (HOMO and LUMO), and relative stabilities for the ligand exchange processes are also examined quantitatively. Schematic diagrams for the dissociation reactions of {PtCl4(H2O)n(n=2,4)}into {PtCl3(H2O)(n-2) + Cl-(H2O)2} and the binding energies {PtCl4(H2O)n(n = 1-5)} of PtCl4 with water molecules are drawn. The geometrical structures, potential energy surfaces, and energetics for the ligand exchange reactions of tetracoordinated platinum (PtY2L2 : Y, L=Cl-, OH-, OH2, NH3) complexes in the ligand-solvent interaction systems were investigated using the ab initio Hartree-Fock (HF) and Density Functional Theory (DFT) methods. The potential energy surfaces for the ligand exchange reactions used for the conversions of (PtCl4 + H2O) to [PtCl3(H2O) + Cl-] and [Pt(NH3)2Cl2 + H2O] to [Pt(NH3)2Cl(H2O) + Cl-] were investigated in detail. For these two exchange reactions, the transition states ([PtY2L2…L']) correspond to complexes such as (PtCl4갤H2O) and [Pt(NH3)2Cl2갤H2O], respectively. In the transition state, ([PtCl4갤H2O] and [Pt(NH3)2Cl2갤H2O]) have a kind of 6-membered (Pt-Cl갤HOH갤Cl) and (Pt-OH갤Cl갤HN) interactions, respectively, wherein a central Pt(II) metal directly combines with a leaving Cl- and an entering H2O. Simultaneously, the entering H2O interacts with a leaving Cl-. No vertical one metal-ligand interactions ([PtY2L2갤L']) are found at the axial positions of the square planar (PtY2L2) complexes, which were formed via a vertically associative mechanism leading to D3h or C2v-transition state symmetry. The geometrical structure variations, molecular orbital variations (HOMO and LUMO), and relative stabilities for the ligand exchange processes are also examined quantitatively. Schematic diagrams for the dissociation reactions of {PtCl4(H2O)n(n=2,4)} into {PtCl3(H2O)(n-2) + Cl-(H2O)2} and the binding energies {PtCl4(H2O)n(n = 1-5)} of PtCl4 with water molecules are drawn. KCI Citation Count: 9