Why does ferrous iron make 6 covalent bonds?

[sameeralord]

Hello everyone,

Is their simple reason for this. Like how there must be 8 electrons in outer shell,I know that is very basic and probably not applicable, or is this something to do with sub shells etc.

Also in billirubin metabolism. Why do red blood cells produce hemin which is iron in ferrous state. Normally in body shouldn't the iron be in in ferric form to function.

Thanks

 

[Borek]

Check out http://en.wikipedia.org/wiki/Crystal_field_theory - it doesn't tell anything about covalent bonds, yet it nicely explains many complexes.