\documentclass{ppex}
\nonstopmode
\usepackage {m-chemic}
\pagestyle{empty}
\setlength\textwidth{207.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage {m-chemic}
\startchemical
  \chemical[SIX,ROT2,B,R6,%
            SUB1,FIVE,B,R4]
\stopchemical
\end{document}
