A quantum chemical study of the effect of substituents in governing the strength of the S–F bonds of sulfenyl-type fluorides toward homolytic dissociation and fluorine atom transfer

The gas-phase homolytic S–F bond dissociation energies (BDEs) of 21 sulfenyl-type fluorides (RSF) have been obtained using the W1w thermochemical protocol. The BDEs (at 298K) for the species in this set range from 316.2 (HCCSF) to 368.1 (H₂CCHSF) kJ mol^–1. We additionally report fluorine-transfer energies (FTEs), corresponding to the energetics of fluorine transfer from RSF to H₂S. At 298K, the FTEs range from –10.7 (H₂AlSF) to 90.7 (MeHNSF) kJ mol^–1. We have also assessed the performance of a wide range of density functional theory (DFT) and double-hybrid DFT methods (in conjunction with the A'VQZ basis set) for the calculation of these quantities. For the calculation of S–F BDEs, the M06-2X procedure offers the best performance, with a mean absolute deviation (MAD) of 1.6kJ mol^–1, whilst for the FTEs, B2K-PLYP and DSD-PBEP86 offer the best performance with MADs of 0.5kJ mol^–1.