Metal Complexes with Macrocyclic Ligands. Part XL. Syntheses and silver(I) complexes of mono- and disubstituted dithiadiazamacrocycles

✍ Scribed by Pascale C. Riesen; Thomas A. Kaden

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: German
• Weight: 499 KB
• Volume: 78
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19950780522

✦ Synopsis

Abstract

A series of N~2~S~2~‐macrocycles with ring sizes varying between 12 and 16, as well as two 12‐membered N~2~S~2~‐rings with a pendant carboxylic and amino group, respectively, were synthesized. Their complexation properties towards Ag^+^ were studied by pH titrations and by potentiometry with a silver electrode. The observation that 1:1 ([AgLH~2~]^3+^, [AgLH]^2+^, [AgL]^+^) and 1:2 species ([AgL~2~H~2~]^3+^, [AgL~2~H]^2+^, [AgL~2~]^+^) were formed is interpreted by postulating that Ag^+^ can bind either to the S‐donors only, or to both the N‐ and S‐atoms. The most stable complex [AgL]^+^ in the series of the nonfunctionalized macrocycles was found for the 12‐membered N~2~S~2~‐ring 3. The stability of it increased when an additional donor group was introduced into the side chain. The highest formation constant (logβ~110~ = 14.43(1)) was obtained with the 12‐membered ring 12 carrying the ethanamine side chain. In view of a radiochemical application, all Ag^+^ complexes were tested in blood serum for their stability, but were not stable enough against transmetallation.