\documentclass{ppex}
\nonstopmode
\AtBeginDocument {\setlength \unitlength {0.09pt}}
\usepackage {aliphat}
\pagestyle{empty}
\setlength\textwidth{207.0pt}
\begin{document}
\ResetPreambleCommands
\ReadyForTheFray
\usepackage {aliphat}
\tetrahedral{0==C;1D==O;2==Cl;%
  4==Cl}
\qquad
\tetrahedral[{0+}]{0==N;%
  1==H;2==CH$_3$;3==H;4==H}
\square{0==C;1D==O;2==Cl;4==Cl}
\end{document}
