@Article{JPhysChemA_107_4883, author = {P. Rosa and C. Gouverd and G. Bernardinelli and T. Berclaz and M. Geoffroy}, title = {{Phosphaalkenes with Inverse Electron Density: Electrochemistry, Electron Paramagnetic Resonance Spectra, and Density Functional Theory Calculations of Aminophosphaalkene Derivatives}}, journal= {J. Phys. Chem. A}, ISSN = {1089-5639}, volume= {107}, number= {24}, pages = {4883-4892}, url = {http://pubs.acs.org/cgi-bin/abstract.cgi/jpcafh/2003/107/i24/abs/jp030023a.html}, doi= {10.1021/jp030023a}, abstract = {{Cyclic voltammetry of Mes*P==C(NMe$_2$)$_2$ (1) and Mes*P==C(CH$_3$)NMe$_2$ (2) shows that, in solution in DME, these compounds are reversibly oxidized at 395 and 553 mV, respectively. Electrochemical oxidation or reaction of 1 (or 2) with [Cp$_2$Fe]PF$_6$ leads to the formation of the corresponding radical cation, which was characterized by its electron paramagnetic resonance (EPR) spectra. Experimental $^{31}$P and $^{13}$C isotropic and anisotropic coupling constants agree with density functional theory (DFT) calculations showing that the unpaired electron is strongly localized on the phosphorus atom, in accord with the description Mes*P$^{•}$-(C(NMe$_2$)$_2$)$^{+}$. Electrochemical reduction of 1 is essentially irreversible and leads to a radical species largely delocalized on the C(NMe$_2$)$_2$ moiety; this neutral radical results from the protonation of the phosphorus atom and corresponds to Mes*(H)P-$^{•}$C(NMe$_2$)$_2$. No paramagnetic species is obtained by reduction of 2. The presence of the amino groups, responsible for the inverted electron distribution at the P-C double bond (P$^{-}$-C$^{+}$), confers on 1 and 2 redox properties that are in very sharp contrast with those observed for phosphaalkenes with a normal $\pi$ electron distribution (P$^{+}$-C$^{-}$): no detection of the radical anion but easy formation of a rather persistent radical cation. For 1, this radical cation could even be isolated as a powder, 1$^{•+}$PF$_6$$^{-}$. As shown by DFT calculations, this behavior is consistent with the decrease of the double bond character of the phosphorus-carbon bond caused by the presence of the amino groups.}}, year = {2003} }