\documentclass{ppex}
\nonstopmode
\usepackage {m-chemic}
\pagestyle{empty}
\setlength\textwidth{207.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage {m-chemic}
\setupchemical[size=small,
  width=fit,height=5500,under=1500]
\mbox{%
 \startchemical \chemical[SIX,B,ER6,RZ6][0]
 \stopchemical
 \startchemical \chemical[SPACE,PLUS,SPACE]
 \stopchemical \startchemical
  \chemical[FIVE,ROT4,B125,+SB3,-SB4,Z4,%
   SR4,RZ4][N,H]
 \stopchemical
 \startchemical
    \chemical[SPACE,GIVES,SPACE][?]
 \stopchemical \startchemical
  \chemical[SIX,B,EB6,R6,SUB4,FIVE,ROT4,%
    B125,+SB3,-SB4,Z4][N]
 \stopchemical
}
\end{document}
