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 [K4(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 [(Vdouble bond; length as m-dashO)(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.