Iron carbonyl, `Fe(CO)_5` is

Options

A. trinuclear
B. mononuclear
C. tetranuclear
D. dinuclear

Answer

B

Explanation

Key Concept Compounds of transition metal with carbonyls (carbon monoxide) are know as metal carbonyls. These are classified into mononculear, dinuclear, trinuclear and so on based on the number of central metal atoms/ions present in a complex.
Complexes following EAN rule have EAN of central metal/ion equal to nearest inert gas configuration and hence, are stable.
Effective atomic number (EAN) of the metal in a complex is given by
EAN=Atomic number (Z)-Oxidation number (O.N)+2(Coordination number)
=26-0+2(5)=36
Thus, `Fe(CO)_(5)` is a stable complex/ion. Since, there is only one central metal atom present in iron carbonyl, `Fe(CO)_(5)`, thus it is monouclear. The structure of `Fe(CO)_(5)` is shown below :

The examples of dinulear, trinuclear complexes are `CO_(2)(CO)_(18), Fe_(3)(CO)_(12)` respectively.