The electron configuration for the Co3+ ion is [Ar]3d6.  In the [Co(NH3)6]3+ complex ion, what is the total number of electrons that are placed in molecular orbitals to determine the molecular orbital configuration?
a.6b.12c.15.d.18e.21

16.Below is the electronic absorption spectrum for an aqueous solution of [Co(NH3)6]Cl3.  Recall that the wavelength of maximum absorbance in the visible region of the electromagnetic spectrum is due to a transition between the tn and e* energy levels.  What color is this solution?
a.Ultraviolet or infrared
b.Somewhere between blue and blue-green (teal)
c.Probably yellowish green
d.Somewhere between yellow and red (orange)
e.The color can not be determined – the absorption peak responsible for the color has a wavelength below 400 nm and that value is not on the chart.

Absorbed and Apparent Colors of
Compounds at Various Wavelengths
Wavelength (nm) and Color of Absorbed LightComplement Color (Observed)
     400 (violet)   greenish yellow
     450 (blue)     yellow
     490 (blue-green)     red
     570 (yellow-green)     violet
     580 (yellow)     dark blue
     600 (orange)     blue
     650 (red)     green

In the FTIR spectrum of solid [Co(NH3)6]Cl3, several bands are observed that are similar to those measured for other metal ion complexes with ammonia ligands.  Two peaks, at 3270 cm–1 and 3460 cm–1, are the result of stretching vibrational motions.  Another peak is located at 826 cm–1.

17.Which of these two peaks has the higher energy?  E = hc/? = h?
a.3270 cm–1b.3460 cm–1

18.(1 pt)Analogous to the spectrum of the copper coordination compound spectrum, the peak at 826 cm–1 is due to:
a.the asymmetric bend of the ammonia ligand.
b.the asymmetric stretch of the ammonia ligand.
c.the asymmetric bend of a chloride ion.
d.the rocking motion of an ammonia ligand coordinated to the Co3+ ion.
e.the broad “shoulder” near the symmetric bend of the ammonia ligand.