Niobium Complexes Supported by Chalcogen-Bridged [OEO]-Type Bis(phenolate) Ligands (E = S, Se): Synthesis, Characterization, and Phenylacetylene Polymerization.

Trichloro niobium(V) complexes and with the sulfur- or selenium-bridged [OEO]-type bis(phenolate) ligands (E = S, Se) were synthesized and fully characterized on the basis of their NMR spectroscopic data and X-ray crystallographic analysis. In the crystalline state of , the [OSeO]-core of the ligand was coordinated to the niobium center in a -fashion. The corresponding tribenzyl niobium(V) complexes and were also prepared by the reactions of and with 3 equivalents of PhCHMgCl in toluene. The X-ray diffraction analysis of revealed that the distorted six-coordinated niobium center incorporated in the [OSeO]-type ligand took a -fashion, and one benzyl ligand was coordinated to the niobium center by -fashion. Complexes and were tested for the phenylacetylene polymerization that produced poly(phenylacetylene)s (PPAs), oligomers, and triphenylbenzenes (TPBs) depending on the chalcogen atom in the [OEO]-type ligand.