# Showing pi bonding through chemfig

I've tried to make a diagram which shows pi bonding through chemfig, but I was not successful. Here is what I want.
(source: chem1.com)

or

(source: uwaterloo.ca)

Since I was unable to do it with chemfig I decided to do it with tikz. This is the best I could do:

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

\begin{tikzpicture}

.. controls (.5,-.5) and (0,-1) .. (-2.5,0);

.. controls (-.5,-.5) and (.5,-1) .. (2.5,0);

.. controls (-2,3) and (-1.5,2.5) .. (-2.5,0);

.. controls (-2,-3) and (-1.5,-2.5) .. (-2.5,0);

.. controls (-4,2.17) and (-3.5,1.31) .. (-2.5,0);

.. controls (-4,-2.17) and (-3.5,-1.31) .. (-2.5,0);

.. controls (-2+5,3) and (-1.5+5,2.5) .. (2.5,0);

.. controls (-2+5,-3) and (-1.5+5,-2.5) .. (2.5,0);

.. controls (4,2.17) and (3.5,1.31) .. (2.5,0);

.. controls (4,-2.17) and (3.5,-1.31) .. (2.5,0);

\end{tikzpicture}

\begin{tikzpicture}

.. controls (.5,-.5) and (0,-1) .. (-2.5,0);

.. controls (-.5,-.5) and (.5,-1) .. (2.5,0);

.. controls (-4,2.17) and (-3.5,1.31) .. (-2.5,0);

.. controls (-4,-2.17) and (-3.5,-1.31) .. (-2.5,0);

.. controls (4,2.17) and (3.5,1.31) .. (2.5,0);

.. controls (4,-2.17) and (3.5,-1.31) .. (2.5,0);

.. controls (0,2) .. (2.5,3)
.. controls (3,3) and (3.5,2.5) .. (2.5,0)
.. controls (1.5,1) .. (0,1)
.. controls (-2,1) .. (-2.5,0);

.. controls (0,-2) .. (2.5,-3)
.. controls (3,-3) and (3.5,-2.5) .. (2.5,-0)
.. controls (1.5,-1) .. (0,-1)
.. controls (-2,-1) .. (-2.5,-0);
\end{tikzpicture}

\end{document}


The end result is quite satisfactory, but

1. A shorter code would be nice
2. I am not sure how to use node and label pi bond and sigma bond(usage of quoate box would also look good), and label the atoms as well
• This reminds me of something I one did: writelatex.com/read/xmsxvkrcbvjw – cgnieder Oct 28 '13 at 15:57
• You might want to add the standard settings to your tikzpicture environment: \begin{tikzpicture}[every shade/.append style={shading=ball}]. Maybe there is still a more efficient way to do it as you have e.g. two symmetry axes. – strpeter Jan 21 '14 at 8:26

\foreach \i in {-4.5,4.5}