Question

The coordination polyhedron geometry shown belongs to which of the following complexes?

(a) [Co(NH3)6]^3+

(b) [Ni(CO)4]

(c) [CoCl2(en)2]^2+

(d) [Fe(C2O4)3]^3-

This question was posed to me during an internship interview.

My question is taken from Definitions topic in chapter Coordination Compounds of Chemistry – Class 12

Answer 1

Correct option is (b) [Ni(CO)4]

Easiest explanation: The arrangement shown is tetrahedral and CN=4. [Co(NH3)6]^3+ is octahedral with CN=6. Both [CoCl2(en)2]^2+ and [Fe(C2O4)3]^3- have didentate ligands and hence CN=6.