Novel low-valent zirconium porphyrin complexes: syntheses, characterization and X-ray crystal structures of (η5-cyclopentadienyl)zirconium tetraphenylporphyrin and (η2-diphenylacetylene)zirconium octaethylporphyrin

Abstract

Reactions of (por)ZrCl₂ [por = octaethylporphyrinato (oep) or tetraphenylporphyrinato (tpp) dianion] with TlCp and diphenylacetylene in the presence of Na/Hg or Mg produce novel low-valent zirconium porphyrin complexes (por)Zr(η⁵-Cp) 1 and (por)Zr(η²-PhCCPh) 2, respectively; spectroscopic and/or structural data for 1 and 2 are consistent with a formalism in which 1 is a resonance hybrid of a zirconium(III) metal-centered radical and a zirconium(IV) porphyrin radical anion while 2 is a zirconium(II) complex stabilized by a four-electron-donor alkyne ligand.