Cyclobutadiene, C 4 H 4 , is unstable but can be stabilized

Cyclobutadiene, C4H4, is unstable but can be stabilized in complexes such as (C4H4)Fe(CO)3. In such complexes, C4H4 is planar and has equal C-C bond lengths:
(a) After the formation of C-H and C-C σ-bonds in C4H4, what orbitals are available for π-bonding? (b) Assuming D4h symmetry for C4H4, derive the symmetries of the four π-MOs. Derive equations for the normalized wavefunctions that describe these MOs, and sketch representations of the four orbitals.