The derivatized 19- and 20-membered macrocyclic thio crowns 3,6,9,12,15,18-hexathianonadecanol C13H26OS6 (19-aneS6-OH) (1) and 3,6,9,13,16,19-hexathiacycloicosanol C14H28OS6 (20-aneS6-OH) (2) have been synthesized by [1 + 1] cyclization in about 30% yield. The ligands 1 and 2 react readily at room temperature with different silver(I) salts in water and in organic solvents to form in quantitative yields the complexes [Ag(19-aneS6-OH)](+) (3) and [Ag(20-aneS6-OH)](+) (4) for which crystals of X-ray quality were grown by slow diffusion of diethylether into methanol. [Ag(19-aneS6-OH)][CF3SO3] crystallizes in the triclinic space group with Z = 2, a 10.760(1), b = 10.853(2) and c = 11.326(2)Angstrom, and alpha = 78.73(1), beta = 73.47(1), and gamma = 74.99(1)degrees. [Ag(20-aneS6-OH)][BF4] also crystallizes in the triclinic space group with Z = 4. The unit cell constants were determined with a = 10.076(4), b = 10.525(3), and c = 22.135(8)Angstrom, alpha = 93.32(2), beta = 102.43(2), and gamma = 100.32(2)degrees. The complex cations [Ag(19-aneS6-OH)](+) and [Ag(20-aneS6-OH)](+) are coordinated through only four sulfur atoms; thus, a distorted tetrahedral coordination geometry is exhibited. In addition we found a highly asymmetric Ag-S bond lengths distribution throughout all complex cations. The stability constants of [Ag](+) with 1 and 2 and, for comparison with [18-aneS6] (5), have been determined in methanol by potentiometric [Ag](+) measurements. Log K values for the formation of 3, 4, and [Ag(18-aneS6](+) (6) are 12.04 +/- 0.19, 11.49 +/- 0.15, and 12.67 +/- 0.13 respectively. Owing to a comparable macrocyclic effect, the similar log K values are reasonable but, since 6 coordinates octahedrally, not expected. H-1 and C-13 NMR investigations at various temperatures give evidence for fluxional coordinative behavior between all six sulfur atoms in solution. Consequently [Ag(19-aneS6-OH)](+), [Ag(20-aneS6-OH)](+), and [Ag(18-aneS6](+) seem to exhibit principally the same solution structures although the solid structures are very different.