%%
%% The LaTeX Companion, 3ed
%%
%% Example 11-4-42 on page II-180 in "Extra decorations for symbols".
%%
%% Copyright (C) 2022 Frank Mittelbach
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3c
%% of this license or (at your option) any later version.
%%
%% See https://www.latex-project.org/lppl.txt for details.
%%

\documentclass{tlc3examargin}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{135.0pt}

%StartShownPreambleCommands
\usepackage{mathtools}
%StopShownPreambleCommands

\begin{document}
\[       {}^{14}_{2} \mathbf{C} ^{5+}_{2} \quad
   \prescript{14}{2}{\mathbf{C}}^{5+}_{2} \quad
   \prescript{14}{} {\mathbf{C}}^{5+}_{2}        \]
\end{document}