Well, I would imagine that chlorine gas (Cl2) is FTIR silent, as most homonuclear diatomics are - because they have no change in dipole moment when they vibrate. It's possible "chlorine" is referring to hypochlorite (Cl-O), which is often colloquially known as "chlorine" in the context of disinfectants and swimming pool sterilizers. Chlorine would have a Raman spectrum, but I can't imagine why that would be in your FTIR library.
Likewise, NaCl is usually considered to be FTIR silent - they make optical windows out of it for this reason, after all. I suppose it probably has some kind of lattice vibration somewhere, but I don't imagine it's in the typical FTIR spectroscopic range.
So, off the top of my head I can't think of why these would be in your instrument's spectroscopic library. Does the library include spectra for these chemicals?