Two new oxalate salts 0.5{[(C 4 H 7 N 2 ) 3 ] } (1) and [(C 6 H 13 N 2 ) 2 ] (2) have been isolated and characterized by single-crystal X-ray diffraction. Salt 1 crystallizes in the triclinic system, space group P-1 with a = 7.909(14), b = 8.538(14), c = 9.030(15) ??, ?ñ = 115.26 (4)?ø, ?ý = 109.22 (7)?ø, ?? = 95.38 (8)?ø, V = 500.7 (15) ?? 3 and Z = 2. Salt 2 crystallizes in the monoclinic system, space group C2/c with a = 21.376 (4), b = 9.9127 (15), c = 19.046 (3) ??, ?ý = 112.756 (9)?ø, V = 3721.6 (11) ?? 3 and Z = 8. In 1 a hydrogen atom is shared by two O atoms of the hydrogen oxalate and the oxalate has a statistical occupancy of 0.5 on each O site leading to a 1:1 hydrogen oxalate/oxalate mixture in the crystal. One 2-methylimidazolium cation exhibits positional disorder. Hydrogen oxalate/oxalate pairs are linked by cations via N??H?ú?ú?ú(O,O) hydrogen bonds leading to chains, which are then connected through N??H?ú?ú?úO hydrogen bonds yielding a sheet structure. C??H?ú?ú?úO hydrogen bonds are also present in the crystal. In the co- crystal 2, the monoprotonated DABCO and urea molecules are connected to the oxalate through N??H?ú?ú?ú(O,O) bifurcated hydrogen bonds and N??H?ú?ú?úO hydrogen bonds, respectively. Moreover, N??H?ú?ú?úN hydrogen bonds link monoprotonated DABCO to urea molecules in addition to inner C??H?ú?ú?úO oxalate interactions and intermolecular C??H?ú?ú?úO urea hydrogen bonding interactions. The inter-species hydrogen bonding interactions give rise to a supramolecular three-dimensional structure. In both compounds 1 and 2, the oxalate anion is twisted.
Two new oxalate salts 0.5{[(C 4 H 7 N 2 ) 3 ][C 2 O 4 HC 2 O 4 ]} (1) and [(C 6 H 13 N 2 ) 2 ][CH 4 ON 2 ][C 2 O 4 ] (2) have been isolated and characterized by single-crystal X-ray diffraction. Salt 1 crystallizes in the triclinic system, space group P-1 with a = 7.909(14), b = 8.538(14), c = 9.030(15) ??, ?ñ = 115.26 (4)?ø, ?ý = 109.22 (7)?ø, ?? = 95.38 (8)?ø, V = 500.7 (15) ?? 3 and Z = 2. Salt 2 crystallizes in the monoclinic system, space group C2/c with a = 21.376 (4), b = 9.9127 (15), c = 19.046 (3) ??, ?ý = 112.756 (9)?ø, V = 3721.6 (11) ?? 3 and Z = 8. In 1 a hydrogen atom is shared by two O atoms of the hydrogen oxalate and the oxalate has a statistical occupancy of 0.5 on each O site leading to a 1:1 hydrogen oxalate/oxalate mixture in the crystal. One 2-methylimidazolium cation exhibits positional disorder. Hydrogen oxalate/oxalate pairs are linked by cations via N??H?ú?ú?ú(O,O) hydrogen bonds leading to chains, which are then connected through N??H?ú?ú?úO hydrogen bonds yielding a sheet structure. C??H?ú?ú?úO hydrogen bonds are also present in the crystal. In the co- crystal 2, the monoprotonated DABCO and urea molecules are connected to the oxalate through N??H?ú?ú?ú(O,O) bifurcated hydrogen bonds and N??H?ú?ú?úO hydrogen bonds, respectively. Moreover, N??H?ú?ú?úN hydrogen bonds link monoprotonated DABCO to urea molecules in addition to inner C??H?ú?ú?úO oxalate interactions and intermolecular C??H?ú?ú?úO urea hydrogen bonding interactions. The inter-species hydrogen bonding interactions give rise to a supramolecular three-dimensional structure. In both compounds 1 and 2, the oxalate anion is twisted.