Hybridization of central metal ion in [Fe(NH3)4(en)]2+ will be

sp3 dsp2 d2sp3 sp3d2

d2sp3

In [Fe(NH3)4(en)]2+  x + 4(0) + 1(0) = 2 x = 2 26Fe: [Ar]4s23d6 Fe2+: [Ar]3d6  ↑↓ ↑ ↑ ↑ ↑ In presence of strong field ligand,  ↑↓ ↑↓ ↑↓       six donor atoms will use d2sp3 hybrid orbitals and hybridization of central metal ion will be d2sp3.