The tuning of P-donor ligands: the aryl and other pendent group effects (PGEs) revisited.
The tuning of P-donor ligands: the aryl and other pendent group effects (PGEs) revisited.
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P-供体配体的调整：重新审视芳基和其他悬垂基团效应（PGE）。
DOI：
10.1039/b816868g
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发表时间：
2009
影响因子：
4
通讯作者：
A. Poë
中科院分区：
文献类型：
--
作者：
A. Poë
P-供体配体的电子和空间效应可以通过改变连接到磷原子的侧基来改变。然而，亚磷酸酯和其他不含芳基基团的P-供体配体的所谓“芳基效应”可以简单地显示为电子侧基效应（PGE）的额外实例，通过该电子侧基效应，效应被传递到磷原子或通过它们。这些影响是相当不同的sigma-donicity和π-酸度参数所造成的，并严格正比于一个特定类型的悬垂基团的数量。在每种情况下，影响的程度是由观察到的实际性质和预测的基础上，在允许空间和π-酸性效应后，配体的行为以相同的方式作为烷基膦的差异。因此，PGEs对特定的悬垂基团和测量其影响的方法是独特的。在线性自由能关系式中，它们不是一般意义上的“参数”。各种侧基的PGEs来自于由Giering & Prock等人确定的所谓的“芳基效应”，用于垂直电离电位（IP）和P-供体配体的一些其他性质。在几乎所有情况下，PGE都会降低IP，并且还原程度（以eV计）在顺序C（6）F（5）中减小，（-0.67）约Cl（-0.67）<Pyr（-0.53）< Ph（-0.49）< OR（-0.19）< OCH（2）CH（2）Cl（-0.07）< etpb（-0.03）< N（C（4）H（8））（+0.01）。不同的铂族元素被发现为其他P-供体依赖性的属性，虽然它们只是彼此相关。
Electronic and steric effects of P-donor ligands can be modified by varying the pendent groups attached to the phosphorus atoms. However, the so-called "Aryl Effects" of phosphites and other P-donor ligands that contain no aryl groups can be shown simply to be additional examples of electronic Pendent Group Effects (PGEs) by which effects are transmitted to the phosphorus atoms or through them. These effects are quite distinct from those caused by varying sigma-donicity and pi-acidity parameters, and are strictly proportional to the number of pendent groups of a particular type. In each case, the extent of the effect is determined by the difference between the actual property observed and that predicted on the basis that the ligand behaves in the same way as alkyl phosphines after allowing for steric and pi-acidity effects. The PGEs are therefore unique to particular pendent groups and to the method of measuring their effects. They are not "parameters" in the sense of being generally applicable in Linear Free Energy Relationships. The PGEs of a variety of pendent groups are derived from the so-called "aryl effects" determined by Giering & Prock et al. for vertical ionization potentials (IPs) and some other properties of the P-donor ligands. In almost all cases the IPs are reduced by the PGEs, and the extent of the reduction (in eV) decreases in the sequence C(6)F(5) (-0.67) approximately Cl (-0.67) < Pyrr (-0.53) < Ph (-0.49) < OR (-0.19) < OCH(2)CH(2)Cl (-0.07) < etpb (-0.03) < N(C(4)H(8)) (+0.01). Different PGEs are found for other P-donor-dependent properties although they are simply related to each other.