Benko Zoltán, Streubel Rainer, Nyulászi László
Department of Inorganic Chemistry, Budapest University of Technology and Economics, Szent Gellért tér 4, H-1521, Budapest, Hungary.
Dalton Trans. 2006 Sep 28(36):4321-7. doi: 10.1039/b608276a. Epub 2006 Jul 31.
The relative stability of different singlet phosphinidenes (R-P) has been investigated by using isodesmic reactions. The energies of these reactions with several R groups were calculated with DFT and ab initio methods at different levels of theory. The best stabilising effect on the phosphinidene centre is exhibited by the R'2C=N-group, resulting in a singlet ground state. The analysis of the electron density in the parent H2C=N-P, indicates a considerable double bond character of the PN bond. Further tuning of the C=N pi-bond polarity is possible by variation of the R' substituents. Using trimethylsilyl substituents or incorporating the carbon atom in a pi-withdrawing pentafulvene ring the stabilization and the computed singlet triplet separation increases. The thermodynamics and the kinetics of dimerisation reactions of the most stabilised R'2C=N-P indicates that these compounds are likely synthetic targets.
