In Co(NH3)6Cl3, since the complex has a total charge of zero, ammonia has an oxidation number of 0, chlorine has an oxidation number of -1, cobalt has an oxidation number of +3. Therefore, there are four electrons in the d orbital of a cobalt in this complex. Figure 8 gives the possible high spin and low spin combinations for four d orbital electrons. The high spin config- uration has four unpaired electrons and the low spin configuration has two unpaired electrons. Figure 7. High and low spins for cobalt d electrons in Co(NO3)2·6H2O Figure 8. High and low spins for cobalt d electrons in Co(NH3)6Cl3 The cobalt complex containing ammonia was found to be diamagnetic, since the magnetic susceptibility balance returned a negative value, -26,
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The only peak in absorbance is at the lowest end of the visible light spectrum, with a continuous decrease in absorbance as wavelength increases. This coincides with the observation of red as the color of the corresponding solution, since red is at the opposite end of the spectrum. Figure 4 is the spectrum of the cobalt complex with CO3 as its ligand. This complex was observed to be green. This is justified by the dip in absorbance for this complex around the 550 nm mark, since that is the wavelength of green light. The absorbance spectrum of the cobalt complex with H2O ligands is given by figure 5. Its color was observed to be blue. Since there are no major peaks in the absorbance spectrum, it is difficult to use the spectrum to justify or question the validity of this observation. Figure 6 gives the absorbance spectrum of the cobalt complex with ammine ligands. Its observed color was tan, and the spectrum does not contrast this observation, since it shows an absorbance peak near blue light wavelengths and a valley near yellow-orange, or tan, light …show more content…
Weak field ligands should tend towards high spin, since lower splitting energy increases the likelihood that the pairing energy of electrons is higher than the energy difference between d orbitals, and likewise strong field ligands should tend towards low spin. Assuming NO3 and NH3 are low spin ligands implies that any ligand with greater separation energy than these two should also be low spin. Therefore, it is very likely that H2O, ox2-, NO2, and gly are low spin, and somewhat likely that CO3 is low spin. The postulation that CO3 is low spin is weak, since CO3 structurally resembles NO3, but may be weaker than CO3 on the spectrochemical series.
Conclusions
Six cobalt complexes were synthesized in solution with various colors and absorption spectra. Their spectrochemical series was found to be CO3, ox2-, gly, NH3, NO2, and H2O, in order of increasing splitting energy. Two solid cobalt complexes, Co(NO3)2·6H2O and Co(NH3)6Cl3, were found to be, most likely,
The only peak in absorbance is at the lowest end of the visible light spectrum, with a continuous decrease in absorbance as wavelength increases. This coincides with the observation of red as the color of the corresponding solution, since red is at the opposite end of the spectrum. Figure 4 is the spectrum of the cobalt complex with CO3 as its ligand. This complex was observed to be green. This is justified by the dip in absorbance for this complex around the 550 nm mark, since that is the wavelength of green light. The absorbance spectrum of the cobalt complex with H2O ligands is given by figure 5. Its color was observed to be blue. Since there are no major peaks in the absorbance spectrum, it is difficult to use the spectrum to justify or question the validity of this observation. Figure 6 gives the absorbance spectrum of the cobalt complex with ammine ligands. Its observed color was tan, and the spectrum does not contrast this observation, since it shows an absorbance peak near blue light wavelengths and a valley near yellow-orange, or tan, light …show more content…
Weak field ligands should tend towards high spin, since lower splitting energy increases the likelihood that the pairing energy of electrons is higher than the energy difference between d orbitals, and likewise strong field ligands should tend towards low spin. Assuming NO3 and NH3 are low spin ligands implies that any ligand with greater separation energy than these two should also be low spin. Therefore, it is very likely that H2O, ox2-, NO2, and gly are low spin, and somewhat likely that CO3 is low spin. The postulation that CO3 is low spin is weak, since CO3 structurally resembles NO3, but may be weaker than CO3 on the spectrochemical series.
Conclusions
Six cobalt complexes were synthesized in solution with various colors and absorption spectra. Their spectrochemical series was found to be CO3, ox2-, gly, NH3, NO2, and H2O, in order of increasing splitting energy. Two solid cobalt complexes, Co(NO3)2·6H2O and Co(NH3)6Cl3, were found to be, most likely,