Crystal structures, spectroscopic characterization and theorical calculations of the guanidinium and ammonium salts of the insulin-enhancing anion '[V'O IND.2'(dipic)] IND.-' - Parajón-Costa, Beatriz S.; Piro, Oscar E.; Pis-Diez, Reinaldo; Castellano, Eduardo Ernesto; Gonzalez-Baró, Ana C. (Polyhedron, 2006)