Fe and paramagnetic/diamagnetic

[JustinLevy]

I don't understand why people expect iron compounds to have unpaired electrons, just because an iron atom does. Atomic silicon does as well. So do many other atomic species. But it seem fairly rare to get a molecule to have unpaired electrons in the ground state ... so what makes Fe special in that respect.

So I have three questions:
1) Does anyone know of an example of a neutral simple (as in just one Fe atom) molecule containing Fe which is diamagnetic? I'd like to play with it in a quantum chemistry program to see some stuff, so the simplier the better.

2) Does anyone know of an example of a charged simple complex containing Fe which is diamagnetic?

3) Can anyone give me some guiding insight for why some atoms seems special with regards to "causing" unpaired electrons in molecules?


Thanks.

 

[BigJDubs]

1) A simple neutral molecule containing iron that is diamagnetic is FeO. 2) A simple charged complex containing iron that is diamagnetic is the ferric ion (Fe3+).3) For certain elements, including iron, it is easier for the electrons to remain unpaired in molecules than it is for other elements. This is due to the fact that iron has a greater number of possible oxidation states, and so it can more easily form molecules with multiple unpaired electrons. This property is known as spin-orbit coupling, and it allows certain elements, such as iron, to have higher spin multiplicities than other elements.