Synthesis and spectral characterization of alkaline earth metal complexes: Crystal structure of a Ca(II) hippuric acid complex

Alkali and alkaline earth coordination polymers constructed from benzene-1,2,4,5-tetracarboxylic acid and flexible dicarboxylate acid ligands: syntheses, structures and spectroscopic and thermal properties

Two new metal coordination complexes, namely, poly[aqua(μ₆-benzene-1,2,4,5-tetracarboxylic acid-κ⁸O¹:O¹,O²:O^2':O⁴:O⁴,O⁵:O^5')(μ-but-2-enedioato-κ²O¹:O⁴)potassium(I)], [K₂(C₄H₂O₄)(C₁₀H₆O₈)(H₂O)₂]_n or [K₂(fum)(H₄btec)(H₂O)₂]_n, (1), and poly[aqua(μ₈-2,5-dicarboxybenzene-1,4-dicarboxylato-κ¹²O¹:O^1',O²:O²,O^2':O^2':O⁴:O^4',O⁵:O⁵,O^5':O^5')(μ-ethanedioato-κ⁴O¹,O²:O^1',O^2')strontium(II)], [Sr₂(C₂O₄)(C₁₀H₄O₈)(H₂O)₂]_n or [Sr₂(ox)(H₂btec)(H₂O)₂]_n, (2) (H₄btec = benzene-1,2,4,5-tetracarboxylic acid, H₂btec = 2,5-dicarboxybenzene-1,4-dicarboxylate, fum = fumarate and ox = oxalate), have been obtained under hydrothermal conditions by reacting the different alkali and alkaline earth metal salts with H₄btec, fumaric acid (H₂fum) and oxalic acid (H₂ox). Complexes (1) and (2) were structurally characterized by single-crystal X-ray diffraction, IR and UV-Vis spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetic analysis-differential scanning calorimetry (TGA-DSC). Complex (1) displays a two-dimensional (2D) layer with the K⁺ ion in a distorted pentagonal bipyramidal geometry and exhibits a uninodal 6-connected hxl/Shubnikov plane net (3,6) with {3⁶.4⁶.5³} topology. Complex (2) displays a three-dimensional (3D) network structure, in which the Sr²⁺ ion is in a distorted monocapped square antiprism geometry. The framework possess a binodal (5,8)-connected net with the Schläfli symbol {3².4¹⁰.5⁸.6⁴.7⁴}{3².4⁶.5²}₂. The 3D Hirshfeld surfaces and 2D fingerprint plots show that the main interactions are the O...H/H...O intermolecular interactions. Moreover, the thermal decompositions of (1) and (2) in the temperature range 303-1273 K revealed that they both decompose in three steps and transform to the corresponding metal oxide.

Crystal structures of two isostructural bivalent metal N-benzoyl-glycinates

The crystal structures of two coordination compounds of N-benzoyl-glycine, viz. catena-poly[[[di-aqua-bis-(N-benzoyl-glycinato)cobalt(II)]-μ-aqua] dihydrate], {[Co(C9H8NO3)2(H2O)3]·2H2O} n , 1, and catena-poly[[[di-aqua-bis-(N-benzoyl-glycinato)nickel(II)]-μ-aqua] dihydrate], {[Ni(C9H8NO3)2(H2O)3]·2H2O} n , 2, are described. The structures of 1 and 2 were reported previously [Morelock et al. (1979). J. Am. Chem. Soc. 101, 4858-4866] and redetermined in this work to determine the H-atom coordinates. In the isostructural compounds, the central metal is located on an inversion centre and exhibits a distorted octa-hedral geometry. A pair of terminal aqua ligands disposed trans to each other and a pair of monodentate N-benzoyl-glycinate ligands form the square base and account for four of the six vertices of the octa-hedron. A μ2-bridging aqua ligand links the bivalent metals into one-dimensional chains extending along the c-axis direction. The one-dimensional chains stabilized by O-H⋯O hydrogen bonds are inter-linked by N-H⋯O and C-H⋯O hydrogen-bonding inter-actions.