Nicotinamide complex of silver(III) with expanded coordination number

Yunfu Sun, Louis J. Kirschenbaum
2018 Journal of coordination chemistry  
In strongly alkaline media ([OH -]  0.12 M), nicotinamide (nica) forms a complex with squareplanar 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) 2or the sixcoordinate Ag(OH) 5 (nica) 2-. Comparison with the reactions of Ag(OH) 4 with nicotinate ion (nic -) and acetamide under
more » ... milar 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(OH 4 ) -. Oxidation takes place at the pyridine ring, yielding nicotinamide N-oxide. Silver(III) is reduced to monovalent silver.
doi:10.1080/00958972.2018.1497790 fatcat:eboppxtvazbjhm3n3at2a7mpl4