Nitro vs nitrito linkage isomers Essay - 1608 Words

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†¦show more content†¦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) Ï r(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