Nicotinamide complex of silver(III) with expanded coordination number. Issue 11 (3rd July 2018)

• Record Type: Journal Article
• Authors: Sun, Yunfu; Kirschenbaum, Louis J.
• Is Part Of: Journal of coordination chemistry. Volume 71:Issue 11/13(2018)
• Page Start: 1863
• Page End: 1874
• Publication Date: 2018-07-03
• Subjects: Silver(III) -- kinetics -- nicotinamide -- intermediate -- complex; Coordination compounds -- Periodicals; 541.2242
• DOI: 10.1080/00958972.2018.1497790
• Languages: English
• ISSNs: 0095-8972

Abstract

Abstract: In strongly alkaline media ([OH − ] ≥ 0.12 M), nicotinamide (nica ) forms a complex with square-planar Ag(OH)4 − [nica] ≥ 0.05 M. The complex decomposes in seconds to nicotinamide N-oxide. The correlation of maximum absorbance of the complex with concentrations of nicotinamide and hydroxide requires that the complex is either the five-coordinate Ag(OH)4 (H-1 nica ) 2− or the six-coordinate Ag(OH)5 (nica ) 2− . Comparison with the reactions of Ag(OH)4 − with nicotinate ion (nic − ) and acetamide under similar conditions indicates that nicotinamide coordinates with Ag(OH)4 − by the amido group rather than the nitrogen on the pyridine ring or the amido oxygen. Kinetics of the Ag(III)-nica redox reaction are consistent with direct reaction between nicotinamide and uncoordinated Ag(OH4 ) − . Oxidation takes place at the pyridine ring, yielding nicotinamide N-oxide. Silver(III) is reduced to monovalent silver. Graphical Abstract: