Synthesis, Structure, and Crystallization Study of a Layered Lithium Thiophene-Dicarboxylate

A layered lithium carboxylate, Li4[C4H2S­(CO2)2]2[C3H7NO]2, crystallizes under solvothermal conditions
(160–180 °C) from lithium nitrate and the ligand 2,5-thiophenedicarboxylate
in N,N-dimethylformamide as solvent.
Single-crystal X-ray diffraction (Pbca a = 10.0216(18)
Å, b = 18.327(4) Å, c =
24.871(5) Å) shows that the material is constructed from lithium-centered
tetrahedral units linked by edge- and corner-sharing to give tetrameric
clusters. These inorganic building units are linked in two dimensions
by the bidentate ligand to give a layered structure in which additionally
coordinated dimethylformamide projects into the interlayer region.
A study of the crystallization of the material using time-resolved
in situ energy-dispersive X-ray diffraction reveals that the material
crystallizes directly from solution at the reaction temperature following
an induction period. Analysis of the crystallization curves suggests
that nucleation does not extend far into the crystallization period
and that crystal growth is one-dimensional. These findings are corroborated
by the observation of relatively large, anisotropic crystals by scanning
electron microscopy.