I'm currently trying to typeset the ion $\ce{Cr2O7^{2-}}$ with oxidation numbers on. My first thought was to put the oxidation state above the atom, but according to IUPAC, the oxidation state should be in the right superscript. Combined with charge, it looks ugly and wrong:

My current ways of doing this are below

1. The oxidation number in right superscript. Looks weird with both numbers so close.
2. The oxidation number above. Looks better, but is against IUPAC.

My question therefore is: Which is the preffered way to typeset this?

[![The ion typesat in LaTex][1]][1]

Also, I would like to excuse beforehand if this should rather be in tex.stackexchange.

  [1]: http://i.stack.imgur.com/WnyuX.png