In order to be able to search for compounds of interest it is necessary to define a consistent set of definitions to be used in the data tables. A glance at various journals reveals that a variety of conventions are used. A major difference, of course, is that no subscripts or superscripts are used.
Solvent molecules involving oxygen are an exception.
Thus the molecule Hacac forms an anionic ligand acac. Ions are set off with square brackets. The empirical formula begins with carbon and hydrogen, if any, with the remaining atoms in alphabetical order. Single letter symbols precede two letter symbols with the same first letter, e.g., B before Ba. The empirical formula will include all atoms in the title formula including those in solvent molecules that are clearly identified in the structure determination.