The highest energy structures now involve symmetric compression of all three Mg---H distances from the equilibrium geometry toward a trigonal planar structure. The general radial shape of both PES suggests that symmetric compression and elongation of the three M---H bonds is the lowest energy pathway to interconvert the trigonal and hexagonal planar geometries. Hence, these surfaces represent the bonding continuum between hexagonal planar and trigonal planar geometries. Complexes 5 and 6a/6b are experimental snapshots around both ends of this continuum.