The Amide Group as Modulator of Crystalline and Liquid Crystalline Structures in Isocyano-Alkylanilide Silver(I) Complexes

Silver­(I)
complexes [AgX­(CNR] and [Ag­(CNR)2]­X (X = anionic
ligand), containing an amide-functionalized isocyanide, CNR = CN–C6H4–NHCOR, have been synthesized and their
X-ray structures have been determined for [Ag­(X)­(CN–C6H4–NHCOCH3)] (X = NO3–, CF3SO3–)
and [Ag­(CN–C6H4–NHCOCH3)2]­X (X = NO3–, CF3SO3–, BF4–). All the crystal structures show a packing of polymeric chains
formed through Ag–OCamide interactions.
These chains associate in layers through hydrogen bonds involving
the amide group, and by further interactions of the metal ion with
oxygen-donor moieties. Substitution of the Me group in the amide by
a nonyl chain (R = C9H19) leads to neutral [Ag­(NO3)­(CN–C6H4–NHCOC9H19)] and ionic [Ag­(CN–C6H4–NHCOC9H19)2]­X (X = NO3–, CF3SO3–, H25C12OSO3–,
BF4–) mesomorphic complexes. All of them
display smectic liquid crystalline phases compatible with the crystal
structures found for the methyl derivatives, and FTIR/ATR spectroscopy
confirms that the intermolecular interactions observed in the solid
state are preserved in the mesophase.