[V(H2O)6]3+⟶d2sp3 23V:−[Ar]3d34s2 V+3:−[Ar]3d2,n=2 (even number of unpaired e) [Cr(H2O)6]2+⟶sp3d2 24Cr:−[Ar]3d54s1 Cr+2:−[Ar]3d4,n=4 (even number of unpaired e−)
[Fe(H2O)6]3+⟶sp3d2 Fe3+:−[Ar]3d54s0 n=5( odd number of unpaired e−) [Ni(H2O)6]3+⟶sp3d2 Ni:−[Ar]3d84s2 Ni+3:−[Ar]3d7,n=3 (odd number of unpaired e−) [Cu(H2O)6]2+⟶sp3d2 Cu:−[Ar]3d94s0 n=1( odd number of unpaired e−)