252933-18-9Relevant academic research and scientific papers
Stable Organopalladium(II) and Organoruthenium(II) Complexes with Spin-Labeled Phosphine Ligands
Leznoff, Daniel B.,Rancurel, Corinne,Sutter, Jean-Pascal,Rettig, Steven J.,Pink, Maren,Kahn, Olivier
, p. 5097 - 5102 (2008/10/08)
Palladium(II) and ruthenium(II) complexes containing aminoxyl radical-substituted triphenylphosphine ligands are reported. The novel spin-labeled phosphine ligands [(p-(4,4,5,5,-tetramethylimidazolinyl-1-oxyl-3-oxide)phenyl)diphenylphosphine] (1) and [(p-(N-oxyl-tert-butylamino-2-)phenyl)diphenylphosphine] (2) react with PdCl2 to yield trans-Pd[1]2Cl2 and trans-Pd[2]2Cl2 (complexes 3 and 4, respectively), which show exchange-coupled EPR spectra. This through-space, intramolecular coupling provides a method of determining the number of radical phosphines coordinated to the Pd(II) center. Systems with only one coordinated phosphine show EPR spectra typical of the ligand. Phosphine 2 reacts with [(η3-C3H5)PdCl]2 and [(η6-p-cymene)RuCl2]2 to form the mononuclear metal phosphine adducts (η3-C3H5)Pd[2]Cl (5) and (η6-p-cymene)Ru[2]Cl2 (6). All complexes show broad, shifted 1H NMR spectra, and magnetic susceptibility measurements confirm the presence of one (complexes 5, 6) or two (complexes 3, 4) radicals per complex accordingly. The X-ray crystal structures of Pd[2]2Cl2 and (η3-C3H5)Pd[2]Cl are also reported. Complexes 5 and 6 are unusual examples of stable organometallic systems with peripheral free radicals, i.e., spin-labeled organometallics.
