跨曲几何形状的起源在极度结合的过渡金属和主要组分子中
Clark R Landis1, Frank Weinhold
1Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Journal of the American Chemical Society
|June 1, 2006
概括
在Ar'MMAr'分子中的横曲几何学质量挑战了结合的预期. 理论分析揭示了强大的M-M键和混合驱动的结构,解释了这些不寻常的分子形状.
科学领域:
- 计算化学的计算化学
- 无机化学 无机化学
- 量子化学 是一个量子化学.
背景情况:
- 结晶学数据揭示了Ar'MMAr'分子 (M=Ge, Cr) 的意想不到的横曲几何形状.
- 这些几何质量挑战了传统的VSEPR (瓦伦斯电子对排斥) 理论对最大结合的预测.
研究的目的:
- 为了研究Ar'MMAr'分子中跨曲几何学的电子起源.
- 量化分子键序并评估金属-金属 (M-M) 键的程度.
- 阐明驱动这些非线性结构的杂交趋势.
主要方法:
- 使用混合密度函数 (B3LYP/6-311++G) 的计算.
- 自然债券轨道 (NBO) 分析用于量化债券订单和分析电子结构.
- 与已知的多重结合金属化合物进行比较,如[Re2Cl8]2-.
主要成果:
- 对于过渡金属 (M=Cr,Mo,W),五倍M-M债券占主导地位,而主要组元素 (M=Ge) 则表现出三倍债券.
- 横曲结构主要归因于混合化趋势,有利于强大的西格玛键.
- 对于过渡金属来说,sd混合化导致曲联结体排列;对于p块元素来说,增加p字符有利于非线性结构.
结论:
- 观察到的横曲几何形状是强西格玛结合的最佳杂交的结果,而不是缺乏高M-M结合顺序.
- 结合方案表现出类似易斯的特征,但涉及到非常规的轨道相互作用.
- 了解这些结构可以了解主要组和过渡金属化合物的结合.
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