# Connecting two rings in chemfig

I've spent literally all day trying to figure out how to make this work and I'm completely stuck. I'm trying to make something similar to

from this site

and I cannot for the life of me get the bonds between the two rings right. I can get the one on the right okay, but I can't get the one on the left. Furthermore, I can't figure out how to change the "distant bond" lengths so I can offset the back ring correctly so it's all visible. Here is an example of what I have (with the non-essential branches commented out so I could see what the heck is going on). The back ring is only scaled larger so I could see what it was doing. It is ignoring the ?[ringStart] connection in the back ring because it's the 6th bond in a ring of 5. No idea how to massage it to do this and any help would be appreciated.

\documentclass{article}
\usepackage{chemfig}
\begin{document}
\setcrambond{2pt}{}{}
\chemfig{[:18]*5(
(-N?[ringStart](-O_2N))
-[,,,,line width=2pt](>N?[ringEnd](-NO_2))
-[,,,,line width=2pt]%N(-NO_2)
-[,,,,line width=2pt]?[ringTop]
-[,,,,line width=2pt]%N(-O_2N)
-[,,,,line width=2pt])
*5([::36,2.0]-?[ringEnd,1]-N--N-?[ringStart,2])}
\end{document}


And once the connections are correct, I have no idea how to force the offset to create the perspective either.

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Here's a quick try. It's a bit inflexible since all the bond angles are hard coded...

\documentclass{article}
\usepackage{chemfig}
\begin{document}

\setcrambond{2pt}{}{}

\chemfig{
O_2N-[:-18]
N*5(
-[,,,,line width=2pt]?[b]
-[,,,,line width=2pt]
(>[:-18]N(-[:-9]NO_2)-[:126,1.6]
*5(
-N(-NO_2)-?[a]-N(-NO_2)
-(-[:-126,1.6]N?[b,{>}](-[:-171]O_2N))-
)
)
-[,,,,line width=2pt]N(-NO_2)
-[,,,,line width=2pt]?[a,{<}]
-[,,,,line width=2pt]
)
}

\end{document}


Crossing bonds in chemfig might be useful for further customization...

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