Sodium (1R,2S,5S)-2-hydroxy-6,6-dimethylbicyclo[3.1.1]heptane-2-carboxylate pentahydrate

In the title compound, Na+·C10H15O3 −·5H2O, the vertices of a distorted octahedron centred on the Na+ cation are defined by six O atoms of water molecules. The edge-sharing Na(H2O)6 octahedra form a chain extended along the b-axis direction with adjacent Na+ cations related by a twofold screw symmetry operation. The organic anion, which is not in close contact with the Na+ cation, is hydrogen-bonded to an uncoordinated water molecule and to water molecules of the Na(H2O)6 octahedra.

In the title compound, Na + ÁC 10 H 15 O 3 À Á5H 2 O, the vertices of a distorted octahedron centred on the Na + cation are defined by six O atoms of water molecules. The edge-sharing Na(H 2 O) 6 octahedra form a chain extended along the b-axis direction with adjacent Na + cations related by a twofold screw symmetry operation. The organic anion, which is not in close contact with the Na + cation, is hydrogen-bonded to an uncoordinated water molecule and to water molecules of the Na(H 2 O) 6 octahedra.

Related literature
For a crystal structure with similar chains of edge-sharing Na(H 2 O) 6 octahedra, see: Huang et al. (2005).
compound the vertices of a distorted octahedron centred on Na + cation are defined by six O atoms of water molecules. The edge-sharing Na(H 2 O) 6 octahedra form a chain extended along the b axis with the adjacent Na + cations related by twofold screw axis symmetry. Similar chains were observed in sodium pyridine-4-carboxylate tetrahydrate (Huang et al., 2005).

Experimental
Potassium permanganate (0.03 mol) and NaOH (0.015 mol) were dissolved in the mixture of water (21 ml) and t-butylalcohol (9 ml)·While stirring vigorously, enantiomerically pure (-)-β-pinene (0.01 mol) was dropped. The reaction mixture was maintained during 1 to 2 h at temperature of 283-293 K. The reaction was completed when the potassium permanganate reacted completely. The mixture was heated to 353 K,then filtered and the precipitate was washed with hot water. The filtrate was concentrated under vacuum to a volume of 10 ml. After standing for one night in refrigerator the product, sodium nopinate, was filtered and washed with ice water. The crude sodium nopinate was recrystallized from water. Analysis calculated for C 10 H 15 O 3 Na: C 58.25, H 7.28, Na11.17%; found: C 58.23, H 7.25, N 11.15%. Crystals of (I) suitable for single-crystal X-ray analysis were selected directly from the sample after recrystallization.

Refinement
In the absence of signifcant anomalous scattering effects, Friedel pairs were averaged. The chirality of atoms C2, C3 and C5 were assigned from the known hand of the starting material·The H-atoms were included in the riding-model approximation with C-H = 0.96-0.98 Å and O-H = 0.82 Å (O-hydroxy) and 0.85 Å (O-water), and with U iso (H) = 1.2 or 1.5 U eq (C) and U iso (H) = 1.5 (O-hydroxy) or 1.2 (O-water) U eq (O). Friedel pairs were merged for the refinement process.  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 > 2sigma(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.