Early transition metal complexes of dinucleating Pacman ligands:: X-ray crystal structures of mixed-valence VIII/VIV complexes

The use of a Schiff-base calixpyrrole (L) as a dinucleating ligand for early transition metals is described. Salt elimination reactions between the crystallographically-characterised [K-4(THF)(3)(PhMe)(L)] and titanium(III) and vanadium(III) halides form the new dinuclear complexes [(MCl)(2)(L)] (M = Ti, V). Adventitious, and partial, oxidation of [(VCl)(2)(L)] resulted in the formation of the unusual mixed-valence vanadyl complexes [(V=O)(S)(VCl)(L)] (S = THF or pyridine), which both adopt desired Pacman geometries in the solid state in which the oxo ligand is accommodated within the dinuclear molecular cleft. (c) 2006 Elsevier B.V. All rights reserved.