LINEAR-CHAIN FORMATION BY AN OXOVANADIUM(V) COMPLEX OF P-METHYLHEXAHOMOTRIOXACALIX[3]ARENE

The oxovanadium(V) complex 4 can be readily synthesized by the reactio n of the lithium salt of p-methylhexahomotrioxacalix[3]arene trianion 3 with VOCl3. Infrared spectra indicate a terminal V=O for complex 4 i n solution and V=O ... V dative interactions in the solid state consis tent with the formation of a mu-oxo-bridged linear chain polymer 1 (M = V, Y = O, X-3 = trianion of macrocycle 2a). Vanadium-51 NMR spectra indicate increased shielding for the linear chain polymer in the solid state compared to complex 4 in solution. Complex 4 and its linear cha in polymer are proposed to have the oxovanadium group contained within the cup of the macrocycle ligand as shown in structures 5 and 7, resp ectively, where the cone represents macrocycle 2a.