Conceptual density functional theory based intrinsic radical stabilities: Application to substituted silylenes and p-benzynes

Spin-polarized Conceptual DFT descriptors, such as the sum of the spin potentials and the spin-philicity index, are used to characterize the vertical and adiabatic singlet-triplet energy separation of silylenes and p-benzynes. In addition, an (approximately) intrinsic stability scale is constructed for both systems, using a model linking bond dissociation enthalpies to chemical concepts such as the electrophilicity index, Pauling's electronegativity and the stability of the individual radical fragments, used with success in a recent contribution for radical systems. The new stability scales are compared to other scales in the literature and are correlated with the singlet-triplet gaps and the electrophilicity index values for the examined compounds, investigating the relationship between reactivity and stability.