Two Polymeric Compounds Built from Mononuclear and Tetrameric Squarate−Copper(II) Complexes by Deprotonation of 3,3-Bis(2-imidazolyl)propionic Acid (HBIP). Synthesis, Crystal Structure, and Magnetic Characterization of [Cu(HBIP)(BIP)](C4O4)1/2·2H2O and [Cu(BIP)(OH2)4(μ-C4O4)](ClO4)2·4H2O | Publicación