Nicotinamide complex of silver(III) with expanded coordination number |
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Authors: | Yunfu Sun Louis J Kirschenbaum |
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Institution: | 1. Department of Chemistry, University of Rhode Island, Kingston, RI, USALKirsch@chm.uri.edu;3. Department of Chemistry, University of Rhode Island, Kingston, RI, USA |
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Abstract: | AbstractIn 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-1nica)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. |
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Keywords: | Silver(III) kinetics nicotinamide intermediate complex |
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