In summary, we describe the synthesis, characterisation, and bonding analysis of a series of complexes involving the coordination of three {Mg-H} bonds or three {Zn-H} bonds to a central Pd or Pt atom. These species possess a near perfectly flat array of six atoms surrounding the central transition metal and describe points along a continuum between trigonal planar and hexagonal planar geometries. While the Zn analogue is best described as trigonal planar, the Mg analogues display a hexagonal planar geometry. The key MO interactions that describe the hexagonal planar geometry are derived from combination of the dxy and dx2-y2 orbitals with suitable (e' symmetry) ligand SALCs constructed from 1s H AOs and 3s Mg AOs. Between them, these molecular orbitals describe aspects of metalmetal bonding in the hexagonal plane. Consideration of the Walsh diagram that connects hexagonal planar (D3h) and trigonal planar (C3h) geometries suggests that deformation should be a low energy process that occurs with a quantifiable increase in the contribution to ligand-ligand bonding at the expense of metal-ligand bonding. Our analysis also suggests that the hexagonal planar extreme of the bonding continuum will be favoured only in systems with big ionic contributions to the bonding. This insight will hopefully contribute to the future development of complexes with unusual planar geometries by rational design.