Normally, MOPAC reads data from the data-file supplied.  When the name of the data set cannot be changed, the data set to be used can be provided in the fixed data set by use of DATA="<text>".  Thus if the name of the fixed data set is "input.dat", so the only job that can be run is:

MOPAC input.dat

and the job that is to be run is the data set "toluene.mop" in folder "F:\my mopac jobs" then the file input.dat would contain the single line:

DATA="F:\my mopac jobs\toluene.dat"

When the MOPAC job is run, input.dat would be read in, then because 'DATA="F:\my mopac jobs\toluene.dat"' was present, the file toluene.dat would be read in.  The results would be put into files of the type input.<suffix>.