Which of these statements about [Co(CN)6]3− is true?
[Co(CN)6]3− has no unpaired electrons and will be in a low-spin configuration.
[Co(CN)6]3−
Co3+=1s22s22p63s23p63d6
CN− is a strong field ligand and as it approaches the metal ion, the electrons must pair up.
The splitting of the d-orbitals into two sets of orbitals in an octahedral [Co(CN)6]3− may be represented as
Here, for d8 ions, three electrons first enter orbitals with parallel spin put the remaining may pair up in t2g orbital giving rise to low spin complex (strong ligand) field.
∴[Co(CN)6]3− has no unpaired electron and will be in low spin configuration.