# How to vertically align (center) components in a chemical reaction?

is there a way to somehow align the components [-M-] and the arrow so that everything is vertically centered? Thank you in advance!

\documentclass{article}
\usepackage{chemfig}

\begin{document}
\setchemfig{atom sep=3em}
\schemestart
n \arrow{0}[,0]
\chemleft[
\chemfig{M([6]-R|^{+;-})}
\chemright]
\schemestop
\schemestart
\arrow{0}[,0] +  \chemfig{-[@{leftfourth,0.5},0.8]M-[@{rightfourth,0.5},0.8]}
\polymerdelim[delimiters ={[]}, height = 5pt, depth = 13pt, indice = m]{leftfourth}{rightfourth}
\schemestop
\schemestart
\arrow{->[Polymerisation][]}[0,2]
\chemfig{-[@{leftbig,0.5},1]-[@{leftmiddle,-18},0.1]M([6]-R|^{+;-})-[@{rightmiddle,42},0.1]-[@{leftsmall,0.9},1.5]M-[@{rightsmall,0.2},1]-[@{rightbig,0.1},0.3]}
\polymerdelim[delimiters ={[]}, height = 10pt, depth = 45pt, indice = k]{leftbig}{rightbig}
\polymerdelim[delimiters ={[]}, height = 1pt, depth = 11pt, indice = m]{leftsmall}{rightsmall}
\polymerdelim[delimiters ={[]}, height = 3pt, depth = 38pt, indice = n]{leftmiddle}{rightmiddle}
\schemestop

\end{document}


• FYI, once you are happy with the provided answer, you should accept that answer and thus close the question. Otherwise, people might think that the question is still open. – pisoir Mar 24 at 12:12

I have removed two superfluous occurences of \schemestop \schemestart, replaced the + sign by \+ and added an additional invisible arrow between the plus sign and the second rectant:

\documentclass{article}
\usepackage{chemfig}

\begin{document}

\setchemfig{atom sep=3em}
\schemestart
n \arrow{0}[,0]
\chemleft[
\chemfig{M([6]-R|^{+;-})}
\chemright]
\arrow{0}[,0] \+  \arrow{0}[,0] \chemfig{-[@{leftfourth,0.5},0.8]M-[@{rightfourth,0.5},0.8]}
\polymerdelim[delimiters ={[]}, height = 5pt, depth = 13pt, indice = m]{leftfourth}{rightfourth}
\arrow{->[Polymerisation][]}[0,2]
\chemfig{-[@{leftbig,0.5},1]-[@{leftmiddle,-18},0.1]M([6]-R|^{+;-})-[@{rightmiddle,42},0.1]-[@{leftsmall,0.9},1.5]M-[@{rightsmall,0.2},1]-[@{rightbig,0.1},0.3]}
\polymerdelim[delimiters ={[]}, height = 10pt, depth = 45pt, indice = k]{leftbig}{rightbig}
\polymerdelim[delimiters ={[]}, height = 1pt, depth = 11pt, indice = m]{leftsmall}{rightsmall}
\polymerdelim[delimiters ={[]}, height = 3pt, depth = 38pt, indice = n]{leftmiddle}{rightmiddle}
\schemestop

\end{document}

• Thank you very much. =) Appreciated your help! – Rom An Mar 24 at 21:53