Dimethyl-ammonium bis-(3-oxidonaphthalene-2-carboxyl-ato)borate hemihydrate.

The title compound, C(2)H(8)N(+)·C(22)H(12)BO(6) (-)·0.5H(2)O, was synthesized under atmospheric conditions in the presence of dimethyl-formamide acting as a template. The structure is composed of [NH(2)(CH(3))(2)](+) cations, bis-(3-oxidonaphthalene-2-carboxyl-ato)borate anions and water mol-ecules. The water molecule lies on a twofold rotation axis. The stabilization of the crystal structure comes from electrostatic inter-actions and is assisted by inter-molecular O-H⋯O and N-H⋯O hydrogen bonds between the layers.


Experimental
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: Mercury (Macrae et al., 2006); software used to prepare material for publication: publCIF (Westrip, 2008 Owing to their rich structural chemistry and potential applications in mineralogy (Grice et al., 1999) and nonlinear optical materials (Touboul et al., 2003), borates have provided an abounding area of research for over half a century. Boron can form a large variety of compounds due to the complexity of the structures involved. Boron atom coordinate with oxygen not only in fourfold coordination (tetrahedral, BO 4 ) but also in threefold coordination (triangular, BO 3 ). These BO 3 and BO 4 groups favour polymerization via common corners into large polynuclear anion units including isolated or finite clusters, chains, sheets, and networks (Grice et al., 1999). Most borates synthesized and studied to date have been prepared under the templating effect of inorganic cations, such as alkali-metal, alkaline-earth, rare-earth or transition cations. Accordingly, many borate systems taking into account alkali metal, alkaline earth metal, rare-earth, and transition metals have been explored in recent years (Schubert et al., 2000). Currently, studies conducted in this area are primarily focused on improving existing materials utilized and search for new materials. In comparison to inorganic borates, synthesis, crystal structure and application of organic borates seem to be insufficient (Li & Liu, 2006;Zhang & Liu, 2006;Carr et al., 2005;Zhang et al., 2005;Downard et al., 2002;Green et al., 2000). As part of our ongoing study of the synthesis and structure of organoborate complexes (Errington et al., 1999;Tombul et al., 2003;Tombul, Guven, Büyükgüngör et al., 2007), we have prepared a new organically templated borate, (I), using dimethylformamide as the structure-directing agent.
The water molecule is also involved in normal, slightly bent, hydrogen bond with the borate anion at a distance of 3.012 (3)

S2. Experimental
For the preparation of title compound, (I), B(OH) 3 (133 mg, 2.16 mmol,) was carefully added to a stirred DMF (10.0 ml) solution of 3-hydroxynaphthalene-2-carboxylic acid (875 mg, 4.65 mmol) at ambient temperature. The reaction mixture initially gave a brown solution which was stirred at 398 K for 2.5 h until all became a gel-like material. This product was then redissolved in the mixture of MeOH/CH 2 Cl 2 (10 ml; 1:1) and allowed to stand at room temperature for a couple of hours, whereupon transparent and fine crystals were harvested. Yield, 79% (based on B(OH) 3 ); Elemental analysis:

S3. Refinement
The H27 atom was located in a difference map and refined freely. Other H atoms were positioned geometrically and refined using a riding model, with C-H = 0.93-0.96 Å and N-H = 0.9530-1.0035 Å with U iso (H) = 1.2 or 1.5 times U eq (C,N) of the parent atom.

Figure 1
Showing the atom-labelling scheme of (I). Displacement ellipsoids are drawn at the 50% probability level.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. 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.