I need to find a way of putting a Tikz node inside the label of a reaction scheme, allowing me to represent the electron movement from a reagent to a catalyst, such as in this situation:
\documentclass[12pt,paper=a4]{scrartcl}
\usepackage[version=4, arrows=pgf-filled]{mhchem}
\usepackage{chemfig}
\begin{document}
\schemestart
\chemfig{*6(----(-[2]\charge{65:1pt=\:, -15:1pt=\:}{O}-[3,0.7]H)--)}
\arrow{<=>[$\ce{H+}$]}
\chemfig{*6(----(-[2]\charge{90:2pt=+}{O}(-[3,0.7]H)(-[1,0.7]H))--)}
\schemestop
\end{document}
As of now, I did not find anything in the chemfig documentation but I might have missed something. What I want is an arrow from the oxygen atom of the first molecule to the proton above the reaction arrow. How do I do this?