Here it is. chemfig
basically works like Tikz. You can set nodes and use those nodes to draw arrows, etc.
I did the brackets by drawing arcs, and setting nodes on the lines. It would have been easier if each "atom" was a node, but I haven't found anything in the documentation. In any case, if you discover something like that, you can remove the extra nodes and use the atoms themselves as a base for other graphics.
I also added \pgfresetboundingbox
to remove some extra white space that was appearing on the right. Not much, but it was noticeable enough.
Output

Code
\documentclass[margin=10pt]{standalone}
\usepackage{chemfig}
\begin{document}
\chemfig{H-[@{a1}:45]O-[@{a2}:-45]H}\pgfresetboundingbox
\chemmove{\draw[red,thick] (a1)+(-8.3pt,-2.8pt) arc (-180:-90:5pt);}\pgfresetboundingbox
\chemmove{\draw[red,thick] (a2)+(3pt,-7.8pt) arc (-90:0:5pt);}
\end{document}