Synthesis and Isomerization of Nitro and Nitritopentaamminecobalt(III) Chloride, Linkage isomers.

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Synthesis and Isomerization of Nitro and Nitritopentaamminecobalt(III) Chloride, Linkage isomers.

Abstract:

In this experiment two compounds were synthesized, nitropentaamminecobalt(III) chloride and nitritopentaamminecobalt(III) chloride, which are a pair of linkage isomers. The infrared spectra of both compounds were measured to compare, and differentiate the two. Upon inspection, the nitritopentaamminecobalt(III) chloride compound had an asymmetric stretch at 1452cm-1 indicating a Co-ONO bond. Nitropentaamminecobalt(III) chloride does not have this peak, instead it has stretch at 500 - 435 cm-1 indicating a M-N bond, an asymmetric NO2 stretch at 1428cm-1 and a NO2 bend at 595cm-1. In both complexes, there's a presence of ammonia degenerate, symmetric, asymmetric and rocking vibration frequencies.

The infrared spectra of a sample of nitropentaamminecobalt(III) chloride heated in an oven overnight at 110 degrees celcius and pentaamminechlorocobalt(III) chloride were also measured for comparison to the two synthesized products. The heated nitropentaamminecobalt(III) chloride showed identical results to the non heated version, except the peak intensities were slightly less. The peaks on pentaamminechlorocobalt(III) chloride were all present on the infrared spectrum of the two synthesized products.

Introduction:

The bent nitrite ion (NO2-) is an example of an ambidentate ligand, meaning it can form a