Bis{[amino-(iminium-yl)meth-yl]urea} tetra-kis-{2-[(di-methyl-amino)(iminium-yl)meth-yl]guanidine} di-μ6-oxido-tetra-μ3-oxido-tetra-deca-μ2-oxido-octa-oxidodeca-vanadium(V) tetra-hydrate

Abstract

The title compound, (C₄H₁₂N₅)₄(C₂H₇N₄O)₂[V₁₀O₂₈]·4H₂O, is a by-product obtained by reacting ammonium metavanadate(V), metformin hydro-chloride and acetic acid in the presence of sodium hypochlorite, at pH = 5. The crystal structure comprises a deca-vanadate(V) anion (V₁₀O₂₈)^6- lying on an inversion centre in space group P , while cations and solvent water mol-ecules are placed in general positions, surrounding the anion, and forming numerous N-H⋯O and O-H⋯O hydrogen bonds. Metforminium (C₄H₁₂N₅)⁺ and guanylurea (C₂H₇N₄O)⁺ cations display the expected shape. Inter-estingly, in physiology the latter cation is known to be the main metabolite of the former one. The reported structure thus supports the role of sodium hypochlorite as an oxidizing reagent being able to degrade metformin hydro-chloride to form guanylurea.

Keywords: crystal structure; deca­vanadate; hydrogen bond; metformin; vanadium.