In which of the following coordination entities the magnitude of `Deltao` (CFSE in ocetahedral field) will be maximum?

Options

A. `|Co(H_(2)O)_(6)|^(3+)`
B. `|Co(NH_(3))_(6)|^(3+)`
C. `|Co(CN)_(6)|^(3-)`
D. `|Co(C_(2)O_(4))_(3)|^(3-)`

Answer

C

Explanation

As `CN^(-)` is a next strong ligand present just before the strongest ligand CO in the spectro-chemical series, it causes maximum crystal field pairing between `t_(2g) and e_(g)` orbitals in an octahedral field . Hence `|Co(CN)_(3)|^(3-)` has maximum `Delta_(0)` value .