New 1D and 2D metal oxygen connectivities in Cu(II) succinato and glutarato coordination polymers: [Cu₃(H₂O)₂(OH)₂(C₄H₄O₄)₂] · 4H₂O, [Cu₄(H₂O)₂(OH)₄(C₄H₄O₄)₂] · 5H₂O and [Cu₅(OH)₆(C₅H₆O₄)₂] · 4H₂O

Abstract

Two Cu(II) hydroxo succinates [Cu3(H2O)2(OH)2(C4H4O4)2] · 4H2O (1) and [Cu4(H2O)2(OH)4(C4H4O4)2] · 5H2O (2) and one Cu(II) hydroxo glutarate [Cu5(OH)6(C5H6O4)2] · 4H2O (3) have been prepared and structurally characterized by single crystal X-ray diffraction methods. They feature 1D and 2D copper oxygen connectivity of elongated {CuO6} octahedra in "4 + 1 + 1" and "4 + 2" coordination geometries. Within 1, linear trimers of three edge-sharing {CuO6} octahedra are connected into copper oxygen chains, which are bridged by the anti conformational succinate anions to generate 2D layers with mono terminally coordinating gauche succinate anions on both sides. The layers are assembled into a 3D framework by interlayer hydrogen bonds with lattice H2O molecules distributed in channels. Different from 1, the principal building units in 2 are linear tetramers of four edge-sharing {CuO6} octahedra. The tetramers are condensed into copper oxygen chains and the succinate anions interlink them into a 3D framework with triangular channels filled by lattice H2O molecules. The {CuO6} octahedra in 3 are edge-shared to form unprecedented 2D inorganic layers with mono terminally coordinating glutarate anions on both sides. Interlayer hydrogen bonding interactions are responsible for supramolecular assembly of the layers into a 3D framework with lattice H2O molecules in the channels. The inorganic layers in 3 can be described as hexagonal close packing of oxygen atoms with the Cu atoms in the octahedral cavities. The title compounds were further characterized by elemental analyses, IR spectra and thermal analyses.