Citation:
Abstract:
The unsaturated redox-active cluster [Pd(3)(dppm)(3)(CO)](n+) (n = 0,1, or 2) reacts with ethylene dicarboxylic esters and a variety of terminal acetylenes (but not PhC CPh) in all three charge states. In particular, the radical cations [Pd(3)(dppm)(3)(CO)(RC CR')](+) can be produced by several routes: one-electron electrochemical reduction of the dication adducts, comproportionation of the neutral and dicationic adducts, as well as the direct complexation of alkyne to the known radical cation [Pd(3)(dppm)(3)(CO)](+). Compared with the latter, each of the adducts have significantly extended lifetimes and classify as persistent radicals in solution. The alkyne adducts have been characterized by voltammetry (cyclic and rotating disk electrode), by UV-vis titrations and by MALDI-TOF mass spectra from dithranol matrices. Isotropic solution EPR spectra of the adducts with R = R' = MeOC(O) and EtOC(O), as well as those with R' = H and R = C(6)H(5), FC(6)H(4), HC CC(6)H(4), and EtO have been obtained. Full line shape fitting simulations demonstrate that all display coupling to six different (31)P (I = 1/2) and to one to three (106)Pd (I = 5/2) nuclei. The A((31)P) values range from a low of 3.0 x 10(4) to a high of 180.5 x 10(4) cm(-1); this variation is caused by changes in the contribution of P s orbitals to the SOMO resulting from structural distortions of the Pd(3)P(6) core upon alkyne coordination.
Notes:
Times Cited: 4Cugnet, Cyril Dal Molin, Sophie Brevet, David Lucas, Dominique Mugnier, Yves Harvey, Pierre D. Boere, Rene T.