What is meant by eg and t2g energy level.and what is meant by inner and outer complex .how to find charge on the sphere

In an octahederal entity,there is repulsion between the electrons in metal s orbital & electrons of ligand.This repulsion results in splitting of degenerate d orbital. The dx2-y2 &dz2 orbital experience more repulsion as they r directed along the axis & hence Will be raised in energy. The dxy, dxz, dyz will be lowered in energy. This degeneracy results in t2g & eg levels with t2g having dxy, dyz ,dxz & eg having dx2-y2 & dz2In inner complexes inner d orbitals r used.In outer complexes, outer d orbital r used.Hope this helps.😊