Orientation of AgI Ions in Coordination Architectures through Ligand Conformation and Anion Binding: from Polymeric Chains to Discrete Squares

Abstract

Five new complexes containing AgI salts and the ligand 3,4‐dipyridyl ketone (L34) were synthesized and characterized, namely {[AgL34]ClO4}∞ (1), {[AgL34]BF4}∞ (2), {AgL34NO3}∞ (3), {AgL34CF3CO2}∞ (4) and [AgL34CF3SO3]4 (5). Both the anion and the ligand conformation were found to affect the structure packing. This set of 1:1 M/L structures demonstrated the role of anion binding and ligand conformation in determining the molecular architecture; the increasing alignment of cations in neighboring M‐L chains in structures 1–4 can be attributed to the anions' ability to coordinate to AgI cations. The conformation of the ligand was shown to determine whether a discrete or polymeric architecture formed. In complexes 1–4 the N3py atom was in a cis orientation, with 1 and 2 forming offset chains held together in 2‐D sheets. The anion in 3 helped link 1‐D chains together to form double chains with the double chains offset in the 2‐D sheet. Complex 4 was present as a 2‐D sheet, with the bifurcating CF3CO2– anion causing the alignment of the AgI cations within the sheet. Complex 5 was the only discrete species, with L34 adopting a trans arrangement and acting as corner pieces of a molecular square. DFT calculations showed that the two conformations of the free ligand had a difference in energy of only 2.1 kJ mol–1.