Crystal and molecular structure of sodium picrate monohydrate

Abstract

Na+ [C6H2(NO2)3O]− H2O,Mr=269.11, monoclinic,C2/m (No. 12),a=13.065(1),b=20.065(2),c=3.6957(4) A,β=90.75(1)°,V=968.7(1) A3,Z=4,Dm=1.848 g cm−3 (by flotation),Dx=1.845 g cm−3, λ(CuKα)=1.54184 A,μ(CuKα)=17.5 cm−1,F(000)=540,T=295 K,R=0.055,wR=0.060 for 879 observed reflections withI≥2.5σ(I). p]In the structure the picrate anion has exact twofold symmetry, the water molecule has exact mirror symmetry and the two sodium cations occupy special positions on inversion centers at (0, 1/2, 0) and (1/2, 1/2, 1/2). The phenyl ring together with the four substituent N and O atoms is strictly planar, but the phenyl ring is severely distorted from hexagonal symmetry, as is commonly observed in structures containing the picrate fragment. Both sodium ions are eight-coordinated with Na(1) and Na(2) in a cubic and distorted cubic arrangement, respectively. Na(1) coordinates to four charged phenoxide O atoms and four O atoms of nitro groups, and Na(2) to four O atoms of nitro groups and four water molecules. The water molecule donates two hydrogen bonds to symmetry-related O(2) atoms ofortho nitro groups. Two symmetry-related O(3) atoms ofortho nitro groups serve as acceptors in a very unusual asymmetric bifurcated C-H⋯O hydrogen bond.