Five Valence Orbitals of Tetracoordinated Metal

Three distinct structural types are available for a tetracoordinated fragment a square planar structure of D41, symmetry, a nonplanar square pyramid with C4 symmetry, a nonplanar structure with C2 symmetry (which would result from the removal of two cis ligands from an octahedral MLe), and the tetrahedral structure of symmetry Tj. These are shown in Fieure 13.5 in the standard orientation. The orbitals of the D4/, structure 

Movement of all four ligands symmetrically to one side of the plane yields the square pyramidal structure. The highest two orbitals of the D h structure, pz = bxg and ndz = axg, are substantially stabilized, the former by in-phase mixing of the ligand orbitals and the latter by relief of repulsion with the ligand orbitals. In ascending order, the five valence orbitals of the structure are dxy = a2, (nxz.nyz) = e, nz = a, and npz =.  

Movement of the two opposite ligands of the D h structure out of the xy plane yields the tetracoordinated C v fragment. The b g and a g orbitals are again stabilized and one of the members of the eg set is destabilized. The position of the orbitals shown is that 

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