Silver–pyridyl complexes of N-4-X-phenyl-N′-4-pyridyl urea (X = Cl, Br, I, F, H; L1–L5) are crystalline solids of the formula [Ag(L)2](S)(NO3) (S = MeCN) for chloro, bromo and iodo ligands (1–3). Solid solution crystals 7–9 of bromo and iodo derivatives were prepared with L2 : L3 : mixed ligands ratio of 46 : 37 : 17, 65 : 19 : 16 and 94 : 0 : 6 (mixed = bromo–Ag–iodo) in the product. The significance of Ag⋯halogen interaction decreases in the expected order I > Br > Cl in isostructural crystal structures. Interestingly, the polar δ+ region of the C–X bond interacts with nitrate O− in a near-linear approach and the equatorial δ− region approaches Ag+ metal atom at a bent angle, consistent with charge polarization at the heavy halogens. The fluoro and protio ligand silver complexes 4–6 are quite different from structures 1–3. Urea–nitrate N–H⋯O hydrogen bonds have R22(8), R21(6), R43(14) and R44(16) cyclic motifs.
You have access to this article
Please wait while we load your content...
Something went wrong. Try again?