```python
from pyscf import gto, scf, mcscf, dmrgscf
from pyscf.tools import molden

# Define the molecule
mol = gto.Mole()
mol.atom = '''
Fe 0.0000 0.0000 0.0000; 
N  0.0000 0.0000 2.0000; 
N  0.0000 2.0000 0.0000; 
N  2.0000 0.0000 0.0000; 
N  0.0000 0.0000 -2.0000; 
N  0.0000 -2.0000 0.0000; 
N  -2.0000 0.0000 0.0000
'''
mol.basis = 'cc-pVDZ'
mol.spin = 4  # Quintet state
mol.charge = 0
mol.build()

# Perform HF calculation
mf = scf.RHF(mol)
mf.kernel()

# Define the active space
ncas = 16  # Number of active space orbitals
nelecas = (8, 8)  # Number of electrons in active space
# Assuming Fe double d-shell (10 electrons, 5 orbitals), 4s shell (2 electrons, 1 orbital),
# and ligand N 2pz orbitals (6 electrons, 6 orbitals) for metal-ligand pi bond and pi backbond

# Perform CASSCF calculation to get the orbitals
mc = mcscf.CASSCF(mf, ncas, nelecas)
mc.kernel()

# Export active space orbitals to Molden format
with open('active_space_orbitals.molden', 'w') as f:
    molden.header(mf, f)
    molden.orbital_coeff(mf, f, mc.mo_coeff, ene=mc.mo_energy, occ=mc.mo_occ)

# Setup DMRG as the solver for CASSCF
mc.fcisolver = dmrgscf.DMRGCI(mol, maxM=1000)
mc.fcisolver.nroots = 1

# Calculate quintet state energy
e_quintet = mc.kernel()[0]

# Change spin state to triplet and recalculate
mol.spin = 2  # Triplet state
mol.build(False, False)  # Rebuild molecule without reinitializing
mf = scf.RHF(mol)
mf.kernel()
mc = mcscf.CASSCF(mf, ncas, nelecas)
mc.fcisolver = dmrgscf.DMRGCI(mol, maxM=1000)
mc.fcisolver.nroots = 1
e_triplet = mc.kernel()[0]

# Output energies
print(f"Quintet Energy: {e_quintet}")
print(f"Triplet Energy: {e_triplet}")

# Perform DMRG-NEVPT2 calculations (assuming previous CASSCF calculations)
from pyscf import mrpt
nevpt2_quintet = mrpt.NEVPT(mc, root=0).kernel()
mc.spin = 2
nevpt2_triplet = mrpt.NEVPT(mc, root=0).kernel()

print(f"Quintet NEVPT2 Energy Correction: {nevpt2_quintet}")
print(f"Triplet NEVPT2 Energy Correction: {nevpt2_triplet}")
```