Metal ion having either d5ord10 configuration can be filled symmetrically in both t2gandeg orbitals. Co+2 has d7 configuration, Co+3 has d6 configuration. Mn+2 has d5 configuration but CN− is strong field ligand and it will pair the electrons due to which electronic configuration is t2g5eg0.

As F is weak field ligand hence back pairing of electrons do not take place or in case of weak field ligand pairing energy of electrons (P )is greater than crystal field splitting energy in octahedral complex (Δo) i.e.P>Δo , hence electrons will go in eg orbitals, instead of back paired in t2g orbitals.