\documentclass{article}
\usepackage{chemfig}
\begin{document}
% IMHO: bonds to long
\chemfig{**6((-Cl)---(-([2]-([:45]-Cl)([:135]-Cl)-Cl)-[:-30]**6(---(-Cl)---))---)}
\begingroup
% IMHO: atoms to small with respect to the bond length
\footnotesize
\chemfig{**6((-Cl)---(-([2]-([:45]-Cl)([:135]-Cl)-Cl)-[:-30]**6(---(-Cl)---))---)}
\endgroup
% IMHO: better vaule for the bond length
\begingroup
\setatomsep{1.8em}
\chemfig{**6((-Cl)---(-([2]-([:45]-Cl)([:135]-Cl)-Cl)-[:-30]**6(---(-Cl)---))---)}
\endgroup
% for this molecule: use the optional argument of the ring for scaling:
\chemfig{**6([,.7](-Cl)---(-([2]-([:45]-Cl)([:135]-Cl)-Cl)-[:-30]**6(---(-Cl)---))---)}
\end{document}