A study of proposed intermediates in the deoxofluorination of carbonyl groups by SF4

Abstract

The [SF4·O=C(CH3)2]2 and SF4·[O=C(CH3)2]2 adducts were synthesized and characterized at low temperature (LT) using Raman spectroscopy and, in the case of [SF4·O=C(CH3)2]2, single-crystal X-ray diffraction. The X-ray crystal structure of SF4·(O=C10H14)·(HF) was obtained, showing F4S---F−H---O=C10H14 interactions. Adducts of [SF3]+ with acetone, cyclopentanone, and 2-adamantanone were shown by 19F and 1H NMR spectroscopy to exist in solutions below −40 °C. The proposed [SF3·{O=C(CH3)2}3]+ cation was observed at LT by reacting [SF3][AsF6] with excess acetone. Above −40 °C SF4 formation was observed. Protonated ketones, [HO=R]+ (R = C(CH3)2, C5H8, C10H14), and aldehydes, [H(O=CHC6H5)2]+ and [H(O=CHCH3)x]+ (x = 1 or 2), were isolated and characterized in the solid state for the first time. NBO analyses were used to quantify the increase in electrophilicity of the oxonium cations. The AsF5·O=R (R = C(CH3)2, C5H8, C10H14) adducts were synthesized and characterized in solution and solid state using LT NMR and Raman spectroscopies, respectively.