Novel Benzyl- or 4-Cyanobenzyl-Substituted N-Heterocyclic (Bromo)(carbene)silver(I) and (Carbene)(chloro)gold(I) Complexes: Synthesis and Preliminary Cytotoxicity Studies

✍ Scribed by Siddappa Patil; Anthony Deally; Frauke Hackenberg; Leonard Kaps; Helge Müller-Bunz; Rainer Schobert; Matthias Tacke

• Publisher: John Wiley and Sons
• Year: 2011
• Tongue: German
• Weight: 463 KB
• Volume: 94
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.201100107

✦ Synopsis

Abstract

N‐Heterocyclic carbene (NHC) complexes bromo(1,3‐dibenzyl‐1,3‐dihydro‐2__H__‐imidazol‐2‐ylidene)silver(I) (2a), bromo[1‐(4‐cyanobenzyl)‐3‐methyl‐1,3‐dihydro‐2__H__‐imidazol‐2‐ylidene]silver(I) (2b), and bromo[1‐(4‐cyanobenzyl)‐3‐methyl‐1,3‐dihydro‐2__H__‐benzimidazol‐2‐ylidene]silver(I) (2c) were prepared by the reaction of 1,3‐dibenzyl‐1__H__‐imidazol‐3‐ium bromide (1a), 3‐(4‐cyanobenzyl)‐1‐methyl‐1__H__‐imidazol‐3‐ium bromide (1b), and 3‐(4‐cyanobenzyl)‐1‐methyl‐1__H__‐benzimidazol‐3‐ium bromide (1c), respectively, with silver(I) oxide. NHC Complexes chloro(1,3‐dibenzyl‐1,3‐dihydro‐2__H__‐imidazol‐2‐ylidene)gold(I) (3a), chloro[1‐(4‐cyanobenzyl)‐3‐methyl‐1,3‐dihydro‐2__H__‐imidazol‐2‐ylidene]gold(I) (3b), and chloro[1‐(4‐cyanobenzyl)‐3‐methyl‐1,3‐dihydro‐2__H__‐benzimidazol‐2‐ylidene]gold(I) (3c) were prepared via transmetallation of corresponding (bromo)(NHC)silver(I) complexes with chloro(dimethylsulfido)gold(I). The complex 3a was characterized in two polymorphic forms by single‐crystal X‐ray diffraction showing two rotamers in the solid state. The cytotoxicities of all three bromo(NHC)silver(I) complexes and three (chloro)(NHC)gold(I) complexes were investigated through 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2__H__‐tetrazolium bormide (MTT)‐based preliminary in vitro testing on the Caki‐1 cell line in order to determine their IC~50~ values. (Bromo)(NHC)silver(I) complexes 2a–2c and (chloro)(NHC)gold(I) complexes 3a–3c were found to have IC~50~ values of 27±2, 28±2, 34±6, 10±1, 12±5, and 12±3 μM, respectively, on the Caki‐1 cell line.