Question

Discuss each of the following observations: (a) The [CoCl4]2– ion is a regular tetrahedron but [CuCl4]2– has a flattened tetrahedral structure. (b) The electronic absorption spectrum of [CoF6]3– contains two bands with maxima at 11,500 and 14,500 cm–1.

Answer 1

See explanation

Step-by-step explanation:

a) Look at the electronic configuration of both species;

Cu^2+- [Ar] 3d9 4s0

Co^2+- [Ar] 3d7 4s0

We can now see that a Jahn Teller effect occurs in [CuCl4]2– due to its d9 configuration. This Jahn-Teller distortion causes the symmetry of [CuCl4]2– to change from tetrahedral T

d to trigonal pyramidal C3v.

b) This is a consequence of Jahn-Teller effect in [CoF6]3– which makes the Co-F bonds lie along the z-axis and become elongated in comparison to the remaining four Co-F bonds