Chemfig, TikZ, circle diagram

Question

I have a problem with drawing such a complex diagram in using Chemfig (a picture of diagram should be attached) . The Chemfig manual describes how to draw curved and U-type arrows but all my attempts to combine both of them into desired diagram failed. If someone comes up with an idea how to do that I'll be very grateful.

Thank you.

Answer 1

chemfig does not provide curved arrows. It is possible to define something with \definearrow - the documentation gives an example. This is not comfortable to use and is only part of what your scheme has: combined curved arrows.

It is probably possible to define such arrows, too, but I don't believe that they're any more comfortable to use. I would try to avoid them completely and instead use what is available already.

\documentclass{article}
\usepackage{chemfig}
\usepackage{chemmacros}
\chemsetup[ox]{pos=super}
\DeclareChemIUPAC\tBu{\textsuperscript{\textit{t}}Bu}

% \usepackage{showframe}

\begin{document}

\begin{center}
 \small
 \schemestart[,2]
   \chemfig{R_2-\ox{2,Pd}-R_1}
   \arrow(start--)[45]
   \ox{0,Pd}
   \arrow(--X){->[*{0.180} $+$ \chemfig{R_2-X}]}[-45]
   \chemfig{R_2-\ox{2,Pd}-X}
   \arrow(--tBu){->[*{0.0} $+$ NaO\tBu][*{0.180} $-$ NaX]}[-135]
   \chemfig{R_2-\ox{2,Pd}-O\tBu}
   \arrow(@tBu--@start){->}
   %%
   % remember this point, \mbox to actually create an empty node
   \arrow(@tBu--rem1){0}[135,1] \mbox{}
   \arrow(@rem1--)[180]
   \chemfig{
     \tBu O-\chemabove{B}{\qquad\fscrm}
     (-[2]OH)(-[6]OH)(-[3,,,,draw=none]Na^{\fplus})
     -O\tBu
   }
   \arrow(@rem1--){<-}[-120,1.25]
   \chemfig{
     R_1-\chemabove{B}{\qquad\fscrm}
     (-[2]OH)(-[6]OH)(-[3,,,,draw=none]Na^{\fplus})
     -O\tBu
   }
   \arrow{<-}[180,1]
   \chemfig{R_1-B(-[:-60]OH)-[:60]OH}
   %%
   % remember this point, \mbox to actually create an empty node
   \arrow(@start--rem2){0}[45,1] \mbox{}
   \arrow(@rem2--)[135,1]
   \chemfig{R_1-R_2}
 \schemestop
\end{center}

\end{document}