\vbox{% First: Save Fig. 6 and Fig. 7 in separate boxes. \newbox\figsix\setbox\figsix=\structure{ \nopositioncheck\atom{H}\esingle\wmostaromatatom{C} \nnesingle\nmostaromatatom{C} \side{\nnwsingle\atom{C}\side{\nneabove\atom{H}} \side{\nebelow\atom{H}}\wsingle\atom{H}} \esingle\atom{C}\side{\nnesingle\atom{H}}\ssesingle \emostaromatatom{C}\side{\esingle\atom{S}\esingle \wmostaromatatom{C}\nnesingle\atom{C} \side{\nnwsingle\atom{H}}\esingle\nmostaromatatom{C} \side{\nnesingle\atom{H}}\ssesingle\emostaromatatom{C} \side{\esingle\atom{C}\side{\sseabove\atom{H}} \side{\sebelow\atom{H}}\nnesingle\atom{H}}\sswsingle \smostaromatatom{C}\side{\ssesingle\atom{H}}\wsingle \atom{C}\side{\sswsingle\atom{H}}\nnwsingle\phantatom{C}} \sswsingle\atom{C}\side{\ssesingle\atom{H}}\wsingle \smostaromatatom{C}\side{\sswsingle\atom{H}}\nnwsingle \phantatom{C}} \newbox\figseven\setbox\figseven=\structure{\atom{H} \nnebelow\atom{B}\side{\nesingle\atom{H}} \side{\nwsingle\atom{H}}\sseabove\atom{H}\sswevoba\atom{B} \side{\swsingle\atom{H}}\side{\sesingle\atom{H}} \nnwbelow\phantatom{B}} % Second: Use the width of the saved structures for the % figure captions, comment each end-of-line to avoid % additional spacing. \newbox\caption\setbox\caption=\hbox to\hsize{\hss% \hbox to\wd\figsix{\hss\bf Figure~6. \rm % 3,4'-Ditolylsulfide.\hss}\hss\hss% \hbox to\wd\figseven{\hss\bf Figure~7. \rm Diborane.\hss}% \hss} % Third: Print structures and captions. \line{\hss\box\figsix\hss\hss\box\figseven\hss} \medskip \box\caption }