Now showing 1 - 2 of 2
  • Publication
    Effect of substituents in governing the homolytic gas-phase P–H bond dissociation enthalpies of phosphine-type oxides (R1R2P(=O)H)
    (Elsevier BV, 2024) ;
    Balanay, Mannix P

    This study reports the gas-phase homolytic P–H BDEs of a set of 30 phosphine-type oxides (i.e., R1R2P(=O)H) obtained using the W1w thermochemical protocol. We note that the P–H BDEs (at 298 K) of the species in this dataset differ by as much as 157.2 kJ mol–1, with (H2B)2P(=O)H having the lowest BDE (249.3 kJ mol–1) and F2P(=O)H having the highest (406.5 kJ mol–1). Furthermore, using the full set of 30 all-electron, non-relativistic, vibrationless bottom-of-the-well W1w P–H BDEs as reference values, we have identified several well-performing DFT methods that could be applied to the computation of the P–H BDEs of phosphine-type oxides. The best-performing DFTs (in conjunction with the A'VTZ basis set) were shown to be MN12-SX (MAD = 1.7 kJ mol–1) and MN12-L (MAD = 2.7 kJ mol–1).

  • Publication
    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
    (Elsevier BV, 2019) ;
    Balanay, Mannix P

    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.