Recently, I've written a latex document about stereochemistry, but i needed a lot of strange newman projection, I found lots of problem about alkenes.

First of all, I had to draw alkenes, then my problem was about eclipsed configurations and the poor readability of these images.

Can chemmacros' newman module help me?


The answer is no. I made a command that does it for me:

    \def \alkeneangle {-#1}
    \pgfmathsetmacro{\Cdist}{.3*cos(#1*3)^2}        %   rear atom position
    \def \bondlengthfront {1.25}                %   front atom's bond length
    \def \bondlengthback {.95}                  %   back atom's bond length
        \coordinate (C1) at (0,0);
        \draw[draw=none] (C1) -- ++(0+\alkeneangle:\Cdist) coordinate (C2);     %   sposta l'atomo posteriore, vedi Cdist
        \coordinate (C1-1) at (90:\bondlengthfront);
        \coordinate (C1-2) at (210:\bondlengthfront);
        \coordinate (C1-3) at (330:\bondlengthfront);
        \draw[draw=none] (C2) -- ++(+90+\alkeneangle:\bondlengthback) coordinate (C2-1) ;
        \draw[draw=none] (C2) -- ++(-90+\alkeneangle:\bondlengthback) coordinate (C2-2) ;
        \draw (C2)  -- (C2-1);
        \draw[double, double distance=2pt] (C2)  -- (C2-2);
        \draw[fill=white] (C1) circle (.6);         
            (C1) -- (C1-1)
            (C1) -- (C1-2)
            (C1) -- (C1-3);
        \node[inner sep=0,anchor=-90] at (C1-1) {#2} ;  
        \node[inner sep=0,anchor=30] at (C1-2) {#3} ;
        \node[inner sep=0,anchor=150] at (C1-3) {#4} ;
        \node[inner sep=0,anchor=-90+\alkeneangle] at (C2-1) {#5} ;
        \node[inner sep=0,anchor=90+\alkeneangle] at (C2-2) {#6} ;
            (C1) circle (.6);

Some examples:


enter image description here


enter image description here

At the moment I'm working on a command that solves the problems of eclipsed configurations on alkanes' newman projection.

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