Question

Shape of $Fe(CO{)}_5$ is:

• A. octahedral
• B. square planar
• C. trigonal bipyramidal
• D. square pyramidal

Answer 1

The correct option is C trigonal bipyramidal

$CO$ is a neutral ligand. $Fe$ ground state configuration is ${4s}^2{3d}^6$.

Generally, $CO$ is a very strong field ligand. So, irrespective of the central metal atom it will push the electrons to form a low spin complex.

Hence, electrons in $3d$ orbital gets paired up and $4s$ electrons will shift into $3d$ orbital.

Now $5$ $CO$ ligands will fill in one $3d$ orbital, one $4s$ orbital and three $4p$ orbitals forming ${dsp}^3$ hybridization which results in trigonal bipyramidal shape.