Acta Crystallographica Section B

Structural Science

Volume 56, Part 3 (June 2000)

Acta Cryst. (2000). B56, 474-485 [doi:10.1107/S0108768199014718]

Terephthalate salts: salts of monopositive cations

J. A. Kaduk

Abstract: The crystal structures of dilithium, disodium and diammonium terephthalate (1,4-benzenedicarboxylate) have been solved ab initio using Monte Carlo simulated annealing techniques, and refined using synchrotron powder data. The structures of dipotassium terephthalate, potassium hydrogen terephthalate and ammonium hydrogen terephthalate have been refined using single-crystal techniques. Li₂C₈H₄O₄ crystallizes in P2₁/c, with a = 8.35921 (5), b = 5.13208 (2), c = 8.48490 (5) Å, [beta] = 93.1552 (4)°, V = 363.451 (3) Å³, Z = 2. The Li anions are tetrahedrally coordinated and the packing of the terephthalate anions resembles the [bold gamma] -packing of aromatic hydrocarbons. Na₂C₈H₄O₄ crystallizes in Pbc2₁, with a = 3.54804 (5), b = 10.81604 (16), c = 18.99430 (20) Å, V = 728.92 (2) Å³, Z = 4. The coordination of the two independent Na is trigonal prismatic and the terephthalate packing resembles the [beta] packing of hydrocarbons. (NH₄)₂C₈H₄O₄ also crystallizes in Pbc2₁, with a = 4.0053 (5), b = 11.8136 (21), c = 20.1857 (24) Å, V = 955.1 (2) Å³, Z = 4. The cations and planar anions are linked by hydrogen bonds and the packing is a looser version of the [beta] packing. K₂C₈H₄O₂ crystallizes in P2₁/c, with a = 10.561 (4), b = 3.9440 (12), c = 11.535 (5) Å, [beta] = 113.08 (3)°, V = 442.0 (3) Å³, Z = 2. The K is trigonal prismatic and the packing is also [beta] . Both KHC₈H₄O₄ and (NH₄)HC₈H₄O₄ crystallize in C2/c, with a = 18.825 (4) and 18.924 (4), b = 3.770 (2) and 3.7967 (9), c = 11.179 (2) and 11.481 (2) Å, [beta] = 98.04 (3) and 94.56 (5)°, V = 816.8 (3) and 790.9 (3) Å³, respectively, and Z = 4. The packing in the hydrogen-bonded acid salts is also [beta] . Electrostatic interactions among the terephthalate anions appear to be important in determining the crystal packing.

Online 1 June 2000


	Rietveld powder data file (CIF format) (152.2 kbytes) Contains datablock amm2tph

	Rietveld powder data file (CIF format) (431.8 kbytes) Contains datablock li2tph

	Rietveld powder data file (CIF format) (417.3 kbytes) Contains datablock Na2tph01

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