OXOVANADIUM(V) 1,3-PROPANEDIOLATE CHLORIDE COMPLEXES - TETRAMERIC CLUSTERS

The structure of the reaction product of VOCl3 and various 1,3-propanediol derivatives was characterized in solution at various temperatures using multinuclear NMR spectroscopy. Although oxovanadium dialkoxide chlorides tend to be monomeric, 1,3-propanediol derivatives induce cluster formation generating tetrameric complexes with a molecular formula of (VOClL)4 (where L is bidentate). The 1,3-propanediol derivatives preferred to bridge over two (or three) vanadium atoms rather than form a cyclic six-membered ring on one vanadium atom as found with the corresponding phosphorus compounds. When the 1,3-propanediol ligand was asymmetric, several complexes were observed in solution. A hydrolysis product was characterized by X-ray crystallography. The compound crystallizes in the triclinic space group P1BAR with a = 10.003 (2) angstrom, b = 11.462 (3) angstrom, c = 11.699 (2) angstrom, alpha = 65.72 (2)-degrees, beta = 79.81 (2)-degrees, gamma = 81.89 (2)-degrees, V = 1199.7 (4) angstrom3, and Z = 1. The correlation between solution and solid-state structure was determined, and a possible pathway to i he hydrolysis product was suggested. Vanadium is used as a reagent in organic synthesis, however, these studies suggest that altered reactivities may surface in the presence of 1,3-propanediol ligands or substrates. The studies show that the analogy between phosphorus and vanadium breaks down in complexes containing 1,3-propanediol derivatives, reducing the prospects of chemically preparing vanadium analogs of cAMP.