catena-Poly[[[aqua[3-(3-hydroxyphenyl)prop-2-enoato]samarium(III)]-bis[μ2-3-(3-hydroxyphenyl)prop-2-enoato]] monohydrate]

The title SmIII compound, {[Sm(C9H7O3)3(H2O)]·H2O}n, was obtained under hydrothermal conditions. Its structure is isotypic with the analogous Eu complex. The latter was reported incorrectly in space group P1 by Yan et al. [J. Mol. Struct. (2008), 891, 298–304]. This was corrected by Marsh [Acta Cryst. B65, 782–783] to P-1. The SmIII ion is nine-coordinated by O atoms from one coordinating water molecule and the remaining ones from the 3-(3-hydroxyphenyl)prop-2-enoatate anions (one bidentate, two bidentate and bridging, two monodentate bridging), leading to a distorted tricapped trigonal–prismatic coordination polyhedron surrounded by solvent water molecules. In the crystal, extensive intermolecular O—H⋯O hydrogen-bonding interactions and π–π interactions [centroid–centroid separation = 3.9393 (1) Å] lead to the formation of a three-dimensional supramolecular network.


Jing-ke Guo and Yi-Hang Wen Comment
It is well known that metal and appropriate ligand are the keys for construction of metal-organic frameworks. Here we choose 3-hydroxycinnamic acid as a ligand due to its unique ability to form stable chelates in diverse coordination modes. Reserches on the compounds containing metal ions and 3-hydroxycinnamic acid have been reported (Niu et al. (2008); Xue et al.(2007); Ye et al.(2005) Yan et al., in 2008, this was then corrected by Marsh to P-1 in 2009.
As is shown in Fig. 1, the structrue contains only one nine-coordinated Sm (III) ions which is coordinated by eight oxygen atoms from carboxylate groups in four 3-hydroxyphenyl anions and one oxygen atom from the water molecule, leading to a distored tricapped trigonal prism structure surrounded by solvent H 2 O molecule.
In the structure,the 3-hydroxycinnamic acids coordinate via three chelating carboxylate groups and two oxygen atoms

Experimental
A mixture of Sm(NO 3 ) 3 (0.1682 g, 0.5 mmol),3-hydroxycinnamic acid (0.2462 g, 1.5 mmol) and 4,4-bipyridine (0.2343 g, 1.5 mmol) was dissolved in a 16 mL EtOH/H 2 O(v/v,1:15) and then sealed in a 25 ml stainless steel reactor with a telflon liner and heated at 413 K for 72 h, and then cooled to room temperature over 3 days. Then, the reactor was cooled to room temperature at a speed of 5 degrees per hour. Yellow single crystals of title compound were obtained by slow evaporation of the filtrate over a few days.

Refinement
The carbon-bound H-atoms were positioned geometrically and included in the refinement using a riding model  (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg, 1999); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figure 1
The molecular structure of title compound. Displacement ellipsoids are drawn at the 30% probability level. View of the supramolecular network conneted by hydrogen bonds.  Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.