For q-bit applications based on coordination complexes, invariance in zero-field splitting parameters upon structural distortions is desired. Here, by employing ab initio calculations, we have probed the origin of such resistance observed in four coordinate [FeII(C3S5)2]2- complexes. While unaltered D parameters are noted for a short range of structural distortions such as dihedral angle, if a wider range is chosen, larger variations are prominent in both D and E/D values.