Anisotropic Templating Effect in the Formation of Two-Dimensional Anionic Cadmium−Thiocyanate Coordination Solids [(12C4)₂Cd][Cd₂(SCN)₆] and [(12C4)₂Cd][Cd₃(SCN)₈] with Checkerboard and Herringbone Patterns, Respectively

This paper reports the syntheses, characterization, and structures of two new two-dimensional cadmium−thiocyanate coordination solids [(12C4)2Cd][Cd2(SCN)6] (1) and [(12C4)2Cd][Cd3(SCN)8] (2), where 12C4 denotes 12-crown-4, C8H16O4. 1 crystallizes in a monoclinic unit cell, space group C2/c with lattice parameters a = 16.297(3) Å, b = 26.267(3) Å, c = 16.296(2) Å, β = 90.20(1)°, and Z = 8. 2 crystallizes in a monoclinic unit cell, space group P21/n with lattice parameters a = 11.604(7) Å, b = 11.366(7) Å, c = 15.736(4) Å, β = 92.84(3)°, and Z = 2. The structure of 1 exhibits a two-dimensional tetragonal motif consisting of Cd2 units arranged in a checkerboard pattern with the dimeric [Cd2(SCN)6]2- complex as the building block. The crystal structure of 2 can be described as a two-dimensional hexagonal array of linear trimeric Cd3 units arranged in a herringbone pattern with the [Cd3(SCN)8]2- complex as the building block. In both 1 and 2, the [(12C4)2Cd]2+ dications are housed in cavities within and between the anionic cadmium−thiocyanate layers but with different orientations (“upright” in 1 and “sideways” in 2) with respect to the cadmium−thiocyanate layers, giving rise to an anisotropic templating effect.