Anionic Host Layers Constructed with Guanidinium–Hydrogen Carbonate Dimer 2:1 Rosette-Ribbons and Bridging Carboxylate Connectors

Four new inclusion compounds featuring an anionic layer-type
host
lattice constructed with guanidinium–bis­(hydrogen carbonate)
2:1 rosette-ribbons that accommodate
the same tetra-n-butylammonium guest species have
been obtained and characterized by single-crystal X-ray analysis.
In these crystal structures, an array of rosette-ribbons in parallel
or nearly parallel alignment are cross-linked by selected carboxylate
molecular connectors with effective bridging distances in the range
10.1–19.8 Å: 4,4′-biphenyldicarboxylate, with the
longest separation between its colinear hydrogen-bonding acceptor
sites in [(n-Bu)4N+]6[C­(NH2)3+]6(HCO3–)6[4,4′-C12H8(COO–)2]3·6H2O (1); cyclohexane-1,4-dicarboxylate, with a
nonplanar molecular skeleton in [(n-Bu)4N+]4[C­(NH2)3+]8(HCO3–)6[1,4′-C6H10(COO–)2]3·8H2O (2); 4-cyanobenzoate, with a strong
“Y type” hydrogen-bonding acceptor site at one end and
a weak one at the other in [(n-Bu)4N+]2[C­(NH2)3+]2(HCO3–)2[NCC6H4(COO–)]2·2H2O (3); and 1H-imidazole-4,5-dicarboxylate,
functioning as a multiple hydrogen-bond acceptor in [(n-Bu)4N+]3[C­(NH2)3+]4(HCO3–)4[H+{C3N2H–(COO–)­(COOH)}2] (4). The
resulting planar anionic layer in 1 becomes an undulatory
one in 3 and 4. In 2, adjacent
wavy layers are supported by centrosymmetric cyclic (GM+)2(H2O)4 “double molecular
pillars” to yield a three-dimensional anionic host network.