Question

A) If [M(H20)6]^2+ is red, which of the following complex ions could be yellow in solution?

1) [M(H2O)2Cl4]^2- 2) [M(H2O)4(SCN)2]

B)Which of the following complexes could have the orbital diagram below? (2 unpaired arrows on top row, 1 paired and 2 unpaired on bottom row.)

1) [CoI6]3- 2) [Ni(OH)4]^2- 3) [Fe(CO]6] ^3+

Answer 1

A)

[M(H₂0)₆]²⁺ is octahedral complex its colur depends upon the crystal field spliting enerhy O

If O increases it shows blue shift means high energy side or high frequency side

In the above complexes if we replace H₂O ligand with Cl or SCN among these two ligands SCN strong field ligand shows more O than Cl

Shifting of color from red to yellow means changing light frequency from high frequency to low frequency

Among the complexes [M(H₂O)₂Cl₄] ^2- and  [M(H₂O)₄(SCN)₂]

[M(H₂O)₄(SCN)₂] shows yellow color

B)

Answer is [CoI₆]^3-