COMEDK 2023 Shift 1 Paper

To determine the correct matches between the coordination compounds in Column I and their characteristic features in Column II, let's analyze each compound's central metal ion, their oxidation states and electron configurations, and then connect them with the appropriate characteristic features:
Compound W:[Co(NH3)5‌Cl]Cl2
- Central metal: Cobalt (Co)
Co is in the complex ion, so bonding Co (III) due to two outside Cl−, must bring the oxidation state to +3 . Electron configuration with Co( III) in a low spin complex (due to NH3 ) is typically d6 with a magnetic moment close of 0 since it is diamagnetic or very low.
Compound X:K4[Mn(CN)6]
- Central metal: Manganese (Mn)
Assuming Mn is the central ion and the charge of [Mn(CN)6]4− with each CN−contributing -1. The oxidation state of Mn is +2 . Manganese in this state (Mn2+) will have a d5 configuration. Because CN−ion is a strong field ligand, the complex might be low spin, but d5 will still have a higher magnetic moment.
Compound Y:[CrCl3(py)3]
- Central metal: Chromium (Cr)
With a neutral ligand and typical counting, Cr is in the +3 oxidation state, giving an electron configuration of d3. This typical configuration and being octahedral could have a greater magnetic moment due to having 3 unpaired electrons.
Compound Z:Cs[FeCl4]
- Central metal: Iron (Fe)
The complex ion [FeCl4]−suggests Fe is in the +3 oxidation state (Fe3+), and as such, iron would have a d5 electron configuration, which in a tetrahedral geometry usually retains more unpaired electrons, hence µ=5.92‌BM as more typical.
Now, by matching the above analysis with the characteristic features given:
-W should match with R(d6,µ=0),
X should match with S(d5,µ=5.92‌BM),
Y should match with Q(d3,µ=3.87‌BM),
Z should match with P(d5,µ=5.92‌BM).
Option D correctly matches the compounds:
W=R,‌‌X=S,‌‌Y=Q,‌‌Z=P