A computational study of SbnF5n (n = 1–4): Implications for the fluoride ion affinity of nSbF5

This contributions shows with a series of ab initio MP2 and DFT (BP86 and B3-LYP) computations with large basis sets up to cc-pVQZ quality that the literature value of the standard enthalpy of depolymerization of 1 4 Sb4F20(g) to give SbF5(g) (+18.5 kJ mol−1) [J. Fawcett, J.H. Holloway, R.D. Peacock, D.R. Russell, J. Fluorine Chem. 20 (1982) 9] is by about 50 kJ mol−1 in error and that the correct value of Δ r H depoly . ° ( 1 4 Sb4F20(g)) is +68 ± 10 kJ mol−1. We assign Δ r H depoly . ° , Δ r H ° , Δ r G ° and Δ r G ° values for SbnF5n with n = 2–4 and compare the results to available experimental gas phase data. Especially the MP2/TZVPP values obtained in an indirect procedure that rely on isodesmic reactions or the highly accurate compound methods G2 and CBS-Q are in excellent agreement with the experimental data, and reproduce also the fine experimental details at temperatures of 423 and 498 K. With these data and the additional calculation of [SbnF5n+1]− (n = 1–4), we then assessed the fluoride ion affinities (FIAs) of SbnF5n(g), nSbF5(g), nSbF5(l) and the standard enthalpies of formation of SbnF5n(g) and [SbnF5n+1]−(g): FIA(SbnF5n(g)) = 514 (n = 1), 559 (n = 2), 572 (n = 3) and 580 (n = 4) kJ mol−1; FIA(nSbF5(g)) = 667 (n = 2), 767 (n = 3) and 855 (n = 4) kJ mol−1; FIA(nSbF5(l)) = 434 (n = 1), 506 (n = 2), 528 (n = 3) and 534 (n = 4) kJ mol−1. Error bars are approximately ±10 kJ mol−1. Also the related Gibbs energies were derived. ΔfH°([SbnF5n+1]−(g)) = −2064 ± 18 (n = 1), −3516 ± 25 (n = 2), −4919 ± 31 (n = 3) and −6305 ± 36 (n = 4) kJ mol−1.