Capturing the Trans Influence in Low-Spin d(8) Square-Planar Platinum(II) Systems using Molecular Mechanics.
Capturing the Trans Influence in Low-Spin d(8) Square-Planar Platinum(II) Systems using Molecular Mechanics.
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DOI：
10.1021/ct9001569
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发表时间：
2009-09
影响因子：
5.5
通讯作者：
Anna E. Anastasi;R. Deeth
中科院分区：
文献类型：
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作者：
Anna E. Anastasi;R. Deeth
配位复合物的分子建模继续为力场方法提出挑战。显式或隐式处理的显着d电子效应是强制性的。配体场分子力学是为配位络合物设计的，通过明确地包括配体场稳定能（LFSE），并且它在这里应用于模拟通式PtX 4、PtX 3 Y、cis-PtX 2 Y2和trans-PtX 2 Y2的四配位Pt（II）络合物中的反式影响，其中X和Y是OH 2、H（-）、Cl（-）、Br（-）、PR 3、SH 2、NR 3和吡啶。参数已开发的默克分子力场使用DFT结构和能量作为参考数据。几何变化和相对能量一般都很好地再现，虽然PH 3和H（-）复合物显示偏差。然而，对于膦络合物，用PMe 3代替PH 3解决了所有这些问题，除了其中之一。与低自旋d（8）构型相关的LFSE确保了平面配位，并在所有配体之间提供了电子连接，从而能够正确描述反式影响。NR 3和PR 3与R = H的参数开发工作以及R = Me和Et，在协议与实验和/或DFT结构，显示四面体畸变，甚至配体解离。
Molecular modeling of coordination complexes continues to present challenges for force field methods. Implicit or explicit treatment of the significant d electron effects is mandatory. Ligand field molecular mechanics is designed for coordination complexes by explicitly including the ligand field stabilization energy (LFSE) and it is applied here to model the trans influence in tetracoordinate Pt(II) complexes of general formulas PtX4, PtX3Y, cis-PtX2Y2, and trans-PtX2Y2, where X and Y are OH2, H(-), Cl(-), Br(-), PR3, SH2, NR3, and pyridine. Parameters have been developed within the Merck molecular force field using DFT structures and energies as reference data. Both geometric changes and relative energies are generally well-reproduced although PH3 and H(-) complexes show deviations. However, for phosphine complexes, replacing PH3 with PMe3 resolves all bar one of these. The LFSE associated with the low-spin d(8) configuration ensures planar coordination and provides an electronic connection between all the ligands, thus enabling a correct description of the trans influence. The parameters developed for NR3 and PR3 with R = H work well for R = Me and Et and, in agreement with experimental and/or DFT structures, display either a tetrahedral distortion or even ligand dissociation.