Crystal structures of catena-poly[[μ-aqua-di-aqua(μ3-2-methyl-propano-ato-κ4 O:O,O':O')calcium] 2-methyl-propano-ate dihydrate], catena-poly[[μ-aqua-di-aqua-(μ3-2-methyl-propano-ato-κ4 O:O,O':O')strontium] 2-methyl-propano-ate dihydrate] and catena-poly[[μ-aqua-di-aqua-(μ3-2-methyl-propano-ato-κ4 O:O,O':O')(calcium/strontium)] 2-methyl-propano-ate dihydrate]

Synthesis and crystal structure of a one-dimensional chain-like strontium(II) coordination polymer built of N-methyldi-ethano-lamine and isobutyrate ligands

The one-dimensional coordination polymer (I) [Sr(ib)2(H2mda)] n (Hib = isobutyric acid, C4H8O2, and H2mda = N-methyldi-ethano-lamine, C5H13NO2), namely, catena-poly[[(N-methyldi-ethano-lamine-κ3 O,N,O')strontium(II)]-di-μ2-isobutyrato-κ3 O,O':O;κ3 O:O,O'], was prepared by the one-pot aerobic reaction of [Zr6O4(OH)4(ib)12(H2O)]·3Hib with Sr(NO3)2 and H2mda in the presence of MnCl2 and Et3N in aceto-nitrile. The use of MnCl2 is key to the isolation of I as high-quality colorless crystals in good yield. The mol-ecular solid-state structure of I was determined by single-crystal X-ray diffraction. Compound I crystallizes in the monoclinic space group P21/c and shows a one-dimensional polymeric chain structure. Each monomeric unit of this coordination polymer consists of a central SrII ion in the NO8 coordination environment of two deprotonated ib- ligands and one fully protonated H2mda ligand. The C and O atoms of the H2mda ligand were refined as disordered over two sets of sites with site occupancies of 0.619 (3) and 0.381 (3). Compound I shows thermal stability up to 130°C in air.

Rerefinement of poly[diaquabis(μ3-2-methylpropanoato-κ4 O:O,O′:O′)bis(μ3-2-methylpropanoato-κ3 O:O:O)(μ2-2-methylpropanoato-κ3 O:O,O′)(2-methylpropanoato-κ2 O,O′)trilead(II)]

The crystal structure of the title complex, [Pb3(C4H7O2)6(H2O)2] n , was redetermined on basis of modern CCD-based single-crystal X-ray data at 120 K. The current study basically confirms the previous report [Fallon et al. (1997). Polyhedron, 16, 19–23] at 190 K, but with higher accuracy and precision. In particular, positional disorder of one of the 2-methylpropanoate anions over two sets of sites was resolved, showing a refined ratio of the disorder components of 0.535 (9):0.465 (9). The three independent cations in the structure have coordination numbers of [7 + 1], [6 + 1], and [5 + 3], with O atoms belonging either to carboxylate groups or water molecules. This arrangement leads to the formation of sheets parallel to (\overline{1}01), whereby the hydrophobic 2-methylpropanyl groups of the anions are oriented above and below the hydrophilic sheets to form a layered structure. Within a sheet, hydrogen bonds of the type Owater—H...O are formed, whereas the hydrophobic groups between adjacent layers interact through van der Waals forces.