% Chlorophyll
\documentclass{article}
\pagestyle{empty}
\usepackage{ochem}
\usepackage{german}
\begin{document}
\begin{chemspecial}
include(`utils.inc')
include(`natur.inc')
require("bicyclib")
\end{chemspecial}
\begin{chemistry}
  formula(L,R) {
    saveXY(#0) atom("Mg")
    restoreXY(#0) saveXY(#cur,={N,N})
    ring(,0,H1=3=,,5,-135){
      0: N_ bond(#0);
      1: saveXY(#1);  4: saveXY(#2);
      2: bond(r) atom("R'");
      3: bond(r; r+);
    }
    restoreXY(#0) saveXY(#cur,={N,0}-{0,N})
    ring(,0,H2=4=,,5,135){
      0: N_ bond(=0.5*(#0-#cur),->);
      1: saveXY(#3);  4: saveXY(#4);
      2: bond(r);
      3: saveXY(#9);
    }
    restoreXY(#0) saveXY(#cur,={0,0}-{N,N})
    ring(,0,H4=,,5,45){
      0: N_ bond(#0);
      1: saveXY(#5);  4: saveXY(#6);
      3: bond(r);
      2: bond(r; -150; 150) branch { bond(90,=C) atom("O"); }
         bond(-150) atom("R");
    }
    restoreXY(#0) saveXY(#cur,={0,N}-{N,0})
    ring(,0,H2=,,5,-45){
      0: N_ bond(=0.5*(#0-#cur),->);
      1: saveXY(#7);  4: saveXY(#8);
      2: bond(r);
      3: bond(r; r-,=);
    }
    restoreXY(#1) bond(=0.5*(#8-#1)+{0,n}; #8,=U)
    restoreXY(#3) bond(=0.5*(#2-#3)+{n,0},=U; #2)
    restoreXY(#5) bond(=0.5*(#4-#5)-{0,n},=U) saveXY(#10) bond(#4)
    restoreXY(#7) bond(=0.5*(#6-#7)-{n,0},=U; #6)
    restoreXY(#9) bond(-110) branch { bond(-60,=C) atom("O"); } bond(180)
     branch { bond(-120,,L) atom("H$_3$COOC",R); }
     bond(#10)
  }
\end{chemistry}
\end{document}