Nitro vs nitrito linkage isomers Essay

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Abstract
In this experiment, the nature of linkage isomers will be observed on the example of nitritopentaamminecobalt(III) Chloride and nitropentaamminecobalt(III) Chloride. Their relative stability will be compared on standard conditions and the infrared spectroscopy of both the isomers will be obtained to analyze the characteristic absorption bands for the nitro and nitrito group. Yield for nitritopentamminecobalt(III) Chloride was obtained to be = 1.9221 g(73.24 %) and yield for nitropentamminecobalt(III) Chloride = 0.76 g(76 %)
Introduction
Linkage isomers may arise when one or more of the ligands can coordinate to the metal ion in more than one way. The first reported example of linkage
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A portion of the nitrito complex was placed in the oven at 110 degrees Celsius and was left for a week. The product was observed to have dark green color and the infrared spectrum was obtained for this compound as well using KBr pellets.

Results
Theoretical yield calculations
For [Co(ONO)(NH3)5]Cl2
[CoCl(NH3)5]Cl2 + NaNO2 = [Co(ONO)(NH3)5]Cl2 + NaCl (eqn 1.4) n([CoCl(NH3)5]Cl2) = 2.518 g / 250.4456 = 0.010054 mol n(NaNO2) = 2.5 g / 68.99 = 0.03624 mol
Thus, [CoCl(NH3)5]Cl2 is the limiting agent. n([CoCl(NH3)5]Cl2) = n([Co(ONO)(NH3)5]Cl2) = 0.010054 mol m([Co(ONO)(NH3)5]Cl2) = 0.010054 mol * 260.998 = 2.62407 g
%Yield = 1.9221 g / 2.62407 g = 73.24 %
For [Co(NO2)(NH3)5Cl2
[Co(ONO)(NH3)5]Cl2 = [Co(ONO)(NH3)5]Cl2 (eqn 1.5)
Their molecular weight is same so
% Yield = 0.76 g / 1 g = 76 %

Infrared spectrum table

Table : Absorption bands of the products synthesized
Compound name
Peak(cm-1)
Peak assignment
Literature reference (cm-1)
Chloropentaamminecobalt(III) Chloride
3300.42 (s)
Vas(NH3)
3267 1

3171.33(s)
Vs(NH3)
3174 1

1588.97(m)
Vas(NH3) degenerate
1589 1

1308.34(s)
Vs(NH3) angle deformation
1309 1

859.46(s) ρr(NH3) 850 1

499.027
Vs(Co-N)
485 1
Nitropentaamminecobalt(III) Chloride
3214.3(s)
Vas(NH3)
3200 1

1617(s)
V(as(NH3) degenerate
1615 1

1435.7(s)
Vas(NO2) scissoring

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