Why Tlf3 exists but TlI3 does not exists Share with your friends Share 1 Ravjot Kaur answered this Dear student. In other halides Tl exists in +3 oxidation state, but in TlI3 is exists in +1 state and Iodine exists as I3- hence it is an exception. i.e. Tl+ + I3- --------> TlI3. Regards -16 View Full Answer