Effect of substituents in governing the homolytic gas-phase P–H bond dissociation enthalpies of phosphine-type oxides (R1R2P(=O)H)

This study reports the gas-phase homolytic P–H BDEs of a set of 30 phosphine-type oxides ( i.e. , R 1 R 2 P(=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 (H 2 B) 2 P(=O)H having the lowest BDE (249.3 kJ mol –1 ) and F 2 P(=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 ).