# Insert a colon in a chemical compound using mhchem or any other chem package available in MikTeX

New to LaTeX. I have only been using it for two weeks. I checked if this question was asked before. Can't find anything. I want to add a colon between the Al and NH3. At the moment all I can think of is the ugly hack shown below. Is there a better way of doing this which does not result in the space either side of the colon? Many thanks..

    \documentclass{article}
\usepackage[version=4]{mhchem}
\begin{document}
$$\ce{(CH3)_{6}Al2_{(g)} + 2NH3_{(g)} -> 2(CH3)_{3}Al}:\ce{ NH3_{(s)}}$$
\end{document}


EDIT:I just found out about \colon but is still adds a space after the colon.

With mhchem, you can escape text which you want to include literally by enclosing it in curly braces:
\ce{(CH3)6Al2_{(g)} + 2NH3_{(g)} -> 2(CH3)3Al{:}NH3_{(s)}}

I've also taken the liberty of of removing underscores where they aren't necessary: that's what you're using mhchem for, after all.