4-Methylpyridinium bis(pyrocatecholato-j2O,O0)- borate catechol solvate

# 2004 International Union of Crystallography Printed in Great Britain ± all rights reserved Unlike the previously reported salts of the 4-methylpyridinium cation and the bis(pyrocatecholato)borate anion [Clegg et al. (1998). Acta Cryst. C54, 1875±1880], the title compound, C6H8N + C12H8BO4 C6H6O2, is a solvate containing a molecule of catechol. The crystal packing is in ̄uenced by NÐH O and OÐH O hydrogen bonds.

The molecular structure of (I) is shown in Fig. 1. The crystal structure contains hydrogen bonds between the catechol molecules and the catecholate ligands of the [B(1,2-O 2 C 6 H 4 ) 2 ] À anions. The 4-methylpyridinium cations also form hydrogen bonds to the catechol molecules, producing a ribbon structure (see Fig. 2). These ribbons crosslink through hydrogen bonds between the catecholate ligands and pyridinium cations to form a one-dimensional hydrogen-bonded polymer (see Fig. 3).

Figure 1
The molecular structure of (I), showing displacement ellipsoids drawn at the 50% probability level. The solvent catechol molecule has been transformed by the symmetry operation (x, y, z À 1).

Figure 2
Stick representation (colour code: C grey, H white, O red, B pink, N blue) of the hydrogen-bonded (dashed lines) ribbon polymers formed in (I).
The NH H atom of the pyridinium cation and all hydroxy H atoms were located in difference maps. Distance restraints of 0.88 (3) and 0.84 (3) A Ê were applied to the NÐH and OÐH bond lengths, respectively. Methyl H atoms were located using a rotating group re®nement, with CÐH bond lengths constrained to 0.96 A Ê . All other H atoms were positioned in ideal geometries and re®ned by riding on their carrier atom. All H atoms were assigned displacement parameters equal to 1.5 times (methyl and hydroxyl H atoms) or 1.2 times (all other H atoms) U eq of their parent atom.
Data collection: SMART (Bruker, 2002); cell re®nement: SAINT (Bruker, 2002); data reduction: SAINT and SHELXTL (Bruker, 2002); program(s) used to solve structure: SHELXTL; program(s) used to re®ne structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL. 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.