Change arrow style in chemmacros 5.1

Question

How can I change the arrowstyle etc.? The code below used to work pre v5.0. I've searched around the manual and the net a bit, but didn't really find something useful. Is it even possible in v5.1?

MnWE:

\documentclass{scrartcl}
\usepackage{chemmacros}
\usechemmodule{all}

\chemsetup[chemformula]{arrow-style = {>=stealth',line cap=round,thick}}
\RenewChemArrow{->}{\draw[chemarrow,->] (cf_arrow_start) -- (cf_arrow_end) ;}
\chemsetup[chemformula]{font-spec = {[Numbers={Proportional,Lining}]MinionPro}}

\begin{document}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{reactions}
  M (OR)_{$n$} + H2O                            &-> M (OR)_{$n-1$} OH + ROH                         \\
  (RO)_{$n'$}M-OH + HO-M(RO)_{$n'$} &-> (RO)_{$n'$}M-O-M(RO)_{$n'$} + H2O                   
\end{reactions}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\end{document}

Answer 1

You're trying to change a chemformula property, not a chemmacros one. Prior to v5.1 chemmacros just loaded chemformula so things worked. As of v5.1 chemmacros let's the user choose if he wants to use chemformula or mhchem for typing formulas and reactions, see section 6.2 The chemformula Module for details.

If the user doesn't make a choice then at the end of the preamble chemformula is loaded, anyway. However, this means that without making a choice chemformula's options are not available in the preamble. (I am aware that this is not ideal…)

Possible solutions:

• load \usepackage{chemmacros,chemformula} and use \setchemformula{} instead of \chemsetup[chemformula]{}, or
• add \chemsetup{ formula = chemformula } before changing the arrows, or
• wait for the update to 5.2 and use \usepackage[compatibility=5.0]{chemmacros} (this should work already but doesn't because I didn't take care enough…)

PS: you can set multiple options with one call of \chemsetup:

\chemsetup[chemformula]{
  arrow-style = {>=stealth',line cap=round,thick} ,
  font-spec = {[Numbers={Proportional,Lining}]MinionPro}
}

PPS: if you just want to change the arrow tips of chemformula's arrows you can simply set them:

\pgfkeys{
  cf/.tip = <tip> ,
  left cf/.tip = <tip> ,
  right cf/.tip = <tip>
}

see the TikZ-manual section 16.5 Reference: Arrow Tips for possible choices