-85(15)° XRD; 67-78° DFT). The asymmetry of the hydride positions is due to association of individual hydrides with a single zinc centre. We have previously structurally characterised the palladium analogue 6a and described its geometry as hexagonal planar. 6b also contains an alternating array of hydride and magnesium ligands arranged in a planar geometry around Pt. ) and 1.85(3) Å while those bridging between two Mg sites supported by the b-diketiminate ligand system typically range from ~1.8 -2.0 Å (Figure ). The apparent difference in the structures of 5 and 6a/b is further supported by DFT calculations. Analysis of the NPA charges suggests that the trigonal planar zinc analogue 5 shows less charge separation than the hexagonal planar structure 6a (Table ). The WBIs reflect subtly different bonding within the trigonal or hexagonal plane. For the trigonal planar structure, the covalent interactions between the Zn-H (0.28-0.31) and Pd-Zn (0.14-0.17) bonds are similar, reflecting the s-complex character. Indeed, these WBI values are almost identical for 2b, which supports the formulation of 5 as a tris-σcomplex. For the hexagonal planar structures, the increased ionic contribution to bonding begins to mask the important covalent bonding interactions. Nevertheless, in the case of 6b the metal-ligand interactions are more significant than the ligand-ligand interactions, Pt-Mg (0.12-0.17) > Mg-H (0.09-0.11). For 6a the values are closer. In these cases, the WBI values are different than those of 2a, illustrating a difference in bonding.