Which of the following is a high spin (spin-free) complex ?

Options

A. `[Zn (NH_(3))_(6)]^(2+)`
B. `[Fe(CN)_(6)]^(4-)`
C. `[CoF_(6)]^(3-)`
D. `[Mn(CN)_(6)]^(4-)`

Answer

C

Explanation

`[Zn(NH_(3))_(6)]^(2+) rarr sp^(3)d^(2)` hybridization `rarr` Zero unpaired electrons
`[Fe(CN)_(6)]^(4-) rarr d^(2)sp^(3)` hybridization `rarr` Zero unpaired electrons
`[CoF_(6)]^(3-) rarr sp^(3) d^(2)` hybridization `rarr` Four unpaired electrons
`[Mn(CN)_(6)]^(4-) rarr d^(2) sp^(3)` hybrization `rarr` One unpaired electron A high spin complex (or spin free complex), such as `[CoF_(6)]^(3-)` is one in which th d electrons are arranged according to Hund's rule to give the maximum number of unpaired electrons. Usually outer orbital complexes `(sp^(3)d_(6)^(2))` are high spin (or spin-free) complexes.