解释二价金属离子生成正八面体构型弱场配位化合物的稳定性顺序规律

这是金属配位化合物中的 Irving-Williams 系列。说实话，现存教科书上对此也没有一个明确地解释。但是，如果学了配位场理论或晶体场理论，你可以从各离子的离子半径的规律，以及价电子层的能级大小出发 （假定弱场配体的配位轨道能量固定）。然后考虑配位场中轨道间的相互作用的大小。
这里时wikipedia的一段，供参考：

There are three strands to the explanation of the series.

1. The ionic radius is expected to decrease regularly for Mn2+ to Zn2+. This would be the normal periodic trend and would account for the general increase in stability.
2. The crystal field stabilisation energy (CFSE) increases from zero for manganese(II) to a maximum at nickel(II). This makes the complexes increasingly stable. CFSE for zinc(II) is zero.
3. Although the CFSE for copper(II) is less than for nickel(II), octahedral copper(II) complexes are subject to the Jahn-Teller effect which results in a complex having extra stability.

The actual CFSE values are 0.4Δ for iron, 0.8Δ for cobalt and 1.2Δ for nickel. Δ is the crystal field splitting energy. When the stability constants are quantitatively adjusted