Acid–Base and Metal-Ion-Coordinating Properties of Benzimidazole and Derivatives (= 1,3-Dideazapurines) in Aqueous Solution: Interrelation between Complex Stability and Ligand Basicity

✍ Scribed by Larisa E. Kapinos; Bin Song; Helmut Sigel

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 183 KB
• Volume: 5
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/(sici)1521-3765(19990604)5:6<1794::aid-chem1794>3.0.co;2-4

✦ Synopsis

The stability constants of the 1:1 complexes formed between Mg 2 , Ca 2 , Sr 2 , Ba 2 , Mn 2 , Co 2 , Ni 2 , Cu 2 , Zn 2 , or Cd 2 ( M 2 ) and benzimidazole-type ligands sterically unhindered at the N3 position ( L), namely, benzimidazole, 1-methylbenzimidazole, 5( 6)-chlorobenzimidazole, 6-chloro-5fluorobenzimidazole, 5(6)-nitrobenzimidazole, 5,6-dichloro-1-(b-d-ribofuranosyl)benzimidazole, and 5,6-dinitrobenzimidazole (DNBI), were determined by UV/Vis spectrophotometry for DNBI and for all the other ligands by potentiometric pH titration in aqueous solutions (25 8C, I 0.5 m, NaNO 3 ). The acidity constants for the monoprotonated ligands HL were also measured. For the HL species which are symmetric with respect to the H(N1) and H(N3) sites, the corresponding micro acidity constants are also given. Plots of log K