New Reactivity of 4‐Amino‐3,5‐bis(pyridin‐2‐yl)‐1,2,4‐triazole: Synthesis and Structure of a Mononuclear Species, a Dinuclear Species, and a Novel Tetranuclear Nickel(II) Rectangle Box, and Magnetic Properties of the Dinuclear and Tetranuclear Complexes | Publicación