Synthesis of a Stannole Dianion Complex Bearing a μ‑η1;η1‑Coordination Mode: Different Electronic State of Stannole Dianion Ligands Depending on Their Hapticity

Reaction of a dilithiostannole with Cp2HfCl2 (Cp = cyclopentadienyl anion, C5H5–) afforded a dinuclear hafnium complex bridged by a stannole dianion ligand, (Cp2ClHf)2[μ-η1;η1-{SnC4(SitBuMe2)2Ph2}]. The product was fully characterized by NMR, elemental analysis, and X-ray diffraction analysis. The product adopts a new coordination pattern in the coordination chemistry of metallole dianion ligands, μ-η1;η1-fashion. Unlike aromatic μ-η5;η5-stannole dianion ligands in triple-decker-type sandwich complexes we previously reported, the stannole ring of the product has 1,3-diene character, revealing its nonaromatic nature. Electronic structures of stannole dianion ligands are therefore strongly affected by their coordination modes.