Estimation of enthalpy data for reactions involving gas phase ions utilizing lattice potential energies:: Fluoride ion affinities (FIA) and pF- values of mSbF5(I) and mSbF5(g) (m=1, 2, 3), AsF5(g), AsF5•SO2(C).: Standard enthalpies of formation:: ΔfH°(SbmF5m+1-,g) (m=1, 2, 3), ΔfH°(AsF6-,g), and ΔfH°(NF4+,g)

Fluoride ion affinity (FIA) values (and the associated pF(-) values) are difficult to establish experimentally for pentafluorides of arsenic and antimony. Our approach, utilizing estimated lattice potential energies, provides a further opportunity to establish this data for liquid (and gaseous) SbF5 and gaseous AsF5 which compliments values obtained using ab initio routes for monomeric gas phase molecules and adds to results based on rigorous methods. A strategy is developed whereby construction of (multiple) Born-Fajans-Haber cycles centered around the (target) FIA reaction of interest yield a plethora of estimates for the enthalpy change of interest. This general approach is illustrated here by specific estimation of some experimentally based FIA values of SbF5 and AsF5. FIA values/kJ mol(-1) and pF(-) values estimated in this paper are FIA(SbF5,I) approximate to -475 (+/-63), pF(-)(SbF5,I) = 11.4 (+/-1.5); FIA(SbF5,g) approximate to -506 (+/-63), pF(-)(SbF5,g) = 12.4 (+/-1.5); FIA(2SbF(5),I) approximate to -609 (+/-63), pF(-) (2SbF(5),I) = 14.6 (+/-1.5); FIA (2SbF(5),g) approximate to -671 (+/-63), pF(-) (2SbF(5),g) = 16.0 (+/-1.5); FIA (3SbF(5),I) approximate to -635 (+/-39), pF(-) (3SbF(5),I) = 15.2 (+/-0.9); FIA (3SbF(5),g) approximate to -728 (+/-39), pF(-) (3SbF(5),g) = 17.4 (+/-0.9); FIA (AsF5,g) approximate to -421 (+/-22), pF(-) (AsF5,g) = 10.1 (+/-0.5); and FIA (AsF5.SO2,s) approximate to -390 (+/-22), pF(-) (AsF5.SO2,s) = 9.3 (+/-0.5). Related standard enthalpies of formation (in W mol(-1)) are also assigned: Delta(f)H(o)(SbF6-,g) approximate to -2075 (+/-52); Delta(f)H(o)(Sb2F11-,g) approximate to -3520 (+/-63); Delta(f)H(o)(Sb3F16-,g) approximate to -4874 (+/-39); Delta(f)H(o)(NF4+,g) approximate to 903 (+/-32); Delta(f)H(o)(AsF6-,g) approximate to -1907 (+/-22).