#4 fractional atoms in formula

[Anonymous]

I work in X-ray crystallography and it is quite common to have molecules, say toluene, sitting on a crystallographic symmetry operator. This results in fractional atoms when considering the unique formula. For instance, in the unit cell is one molecule of C22H20F3N7O3S1 and a toluene (on a symmetry centre) making the unit cell formula C51H48F6N14O6S2 (Z=2). The elemental formula is then C25.5 H24 F3 N7 O3 S1.

It would be very useful if Chemistry::Mol understood and dealt with formulae such as C25.5 H24 F3 N7 O3 S1 or 0.5(C51H48F6N14O6S2)