Diamagnetic contribution charge model

Low-spin iron(II) ions are d with no unpaired electrons and are diamagnetic. The t2g subshell is hilly occupied, which leads to a symmetric charge distribution around the iron nucleus. Therefore, the electronic contribution to the electric held gradient should diminish and as a consequence low-spin iron(II) complexes are expected to have a very small or even undetectable quadrupole splihing. However, this is not always the case. Note that some low-spin ferrous heme proteins as well as heme model complexes have AEq > lmms . For example, for the heme model complex [TMPFe(II)(l,2-Me2lm)2], Aiig = 1.73 mms has been reported. ... 

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