The lattice energy calculations with the Williams 01 potential were calculated with a version of Neighcrys with an atom typing bug. Page 186 col 2 paragraph beginning "Lattice energy calculations" should read
gives the intermolecular lattice energy as -134.7 kJ mol-1 (instead of -133.0) for IR and -133.5 kJ mol-1 (instead of -131.9) for IIO.
Since the energy shift is small and almost constant the conclusions are unaffected.
Link to paper