# Square brackets in chemcompounds custom names

I would like to denote a molecular ion using the chemcompounds package. This would involve wrapping part of a chemcompounds descriptor in square brackets, like so:

$[1]^{2+}$

However, because the chemcompounds name argument is placed between square brackets, trying to do this causes an error.

How is it done?

## MWE

\documentclass[a4paper]{minimal}
\usepackage{chemcompounds}
\declarecompound[J]{c1}
\declarecompound[J$^{+}$]{c1c}
%\declarecompound[[J]$^{+}$]{c1bc}

\begin{document}

This species is denoted \compound{c1}.

This molecular ion is denoted \compound{c1c}.

%This molecular ion breaks chemcompounds: \compound{c1bc}.

\end{document}


(I have commented out the lines that break compilation)

-
It is always best to compose a MWE that illustrates the problem including the \documentclass and the appropriate packages so that those trying to help don't have to recreate it. –  Peter Grill Nov 8 '11 at 2:42

Normally, an extra pair of braces solves this kind of problem:

\documentclass{article}
\usepackage{chemcompounds}

\declarecompound[${[1]^{2+}}$]{label}

\begin{document}

\compound{label}

\end{document}


If this was not the case, while you provide a proper MWE with chemcompounds, I would suggest you to use the mhchem package instead:

\documentclass{article}
\usepackage{mhchem}

\begin{document}

\ce{$[1]^{2+}$}

\end{document}


-
The extra braces fix the problem, thanks. I already use mhchem for formulae, but chemcompounds serves a different role, namely the consistent abbreviation of compounds. –  Richard Terrett Nov 8 '11 at 3:15