Synthesis and Characterization of 1,1′-Diphosphaplumbocenes: Oxidative Ligand Transfer Reactions with Divalent Thulium Complexes

The new 1,1′-diphosphaplumbocenes Pb(Dtp)2 (Dtp = 2,5-di-tert-butyl-3,4-dimethylphospholyl) and Pb(Dsp)2 (Dsp = 2,5-ditrimethylsilyl-3,4-dimethylphospholyl) have been synthesized and characterized by multinuclear NMR spectroscopy. 207Pb NMR spectra of both complexes, as well as for the known complex Pb(Htp)2 (Htp = 2,5-di-tert-butylphospholyl), show that the phospholyl ligands lead to an important downfield shift compared with that of cyclopentadienyl based plumbocenes. X-ray diffraction studies of the Pb(Dtp)2 complex revealed a structure with two slightly bent η5-bound ligands. This complex was employed in the oxidative ligand transfer reaction with bulky divalent thulium complexes. In the case of Tm(Dtp)2, the first example of a monomeric trivalent tris(phospholyl)lanthanide complex Tm(Dtp)3 was obtained. X-ray diffraction studies and low-temperature 1H NMR studies show the η1 coordination mode of the third Dtp ligand. In contrast, oxidation of Tm(Cpttt)2 (Cpttt is for tris-tert-butylcyclopentadienyl) ...