Which of these statements about `[Co(CN)_6]^(3-)` is true?

Options

A. `[Co(CN)_(6)]^(3-)` has no unpaired electrons and will be in a high-spin configuration
B. `[Co(CN)_(6)]^(3-)` has no unpaired electrons and will be in a low-spin configuration
C. `[Co(CN)_(6)]^(3-)` has four unpaired electrons and will be in a lowspin configuration
D. `[Co(CN)_(6)]^(3-)` has four unpaired electtrons and will be in a high-spin configuration

Answer

B

Explanation

Here cobalt is in `+3` oxidation state and has the electronic confuiguration `3d^(6)` . Since `CN^(-)` is a strong field ligand, all the d-electrons are paired leading to `d^(2)sp^(3)` hybridisation. Thus, `[Co(CN)_(6)]^(3-)` having no unpaired electrons is called an inner orbital or low spin or spin paired complex.