Å shorter than that trans to Mg; a likely consequence of the strong trans-effect exerted by the main group atom. The Pd---Mg distance of 2.5469(8) Å is within the sum of covalent radii (Pauling, 2.64 Å; Pyykkö, 2.59 Å). Neutron diffraction studies confirmed the location of the hydride site and allowed the Mg-H and Pd-H bond lengths to be determined as 1.89(5) and 1.70(4) Å respectively. The Pd-H-Mg angle is 89(2)°.