Relationship between electrophilicity and spin-philicity of divalent and monovalent species of group 14 and 15 elements

The relationship between the adiabatic singlet-triplet gap, electrophilicity, nucleophilicity, spin-philicity and spin-donicity indices is investigated for a large number of carbenes, silylenes, germylenes, nitrenes and phosphinidenes. In accordance with the experimental findings, it is shown that with increasing stability of the singlet state of the molecule the electrophilicity decreases in the case of silylenes and germylenes. The electrophilicity index of nitrenes and phosphinidenes shows no direct correlation to their adiabatic singlet-triplet gap. However, a good correlation is found between the adiabatic singlet-triplet gap and the spin-philicity and spin-donicity indices, and this correlation is universal for all investigated molecules independent of their ground state spin multiplicity. The correlation between spin-philicity and electrophilicity indices for silylenes and germylenes is explained in terms of the stability and the electron distribution of the molecule.