\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{graphicx,chemscheme}
\usepackage[inactive,final]{pst-pdf}
\begin{document}
\floatcontentscentre
An example file for PDFLaTeX use.
\begin{scheme}
  \schemeref{IMesHCl}
  \schemeref{IMes}
  \includegraphics{scheme-two}
  \caption{A scheme with automated compound numbers.}
  \label{sc:scheme-one}
\end{scheme}
\end{document}
