Complex 1-Dy exhibits Dy-N distances of 2.205( ) Å (1-Dy-A) and 2.166( and C=C bond lengths (1.300( ) Å for 1-Dy-A, 1.337(17) Å for 1-Dy-B) that are consistent with an unbound C=C double bond (1.34 Å) , leading to one proximal Dy•••Halkene distance (2.519 Å for 1-Dy-A, 2.851 Å for 1-Dy-B). Structurally authenticated Ln alkene and alkyne complexes are rare as these show weak electrostatic interactions . Density-functional theory (DFT) and quantum theory of atoms in molecules (QTAIM) analysis of 1-Y at an optimised geometry confirms that the η 2 -alkene interaction is weak compared to Y-N interactions (electron density, ρ, at the Y-C(alkene) bond critical point is 0.034 a.u., vs ρ ~ 0.085 a.u. at the Y-N critical points), though slightly larger than a previously reported Yb-η 2 -alkyne complex with ρ = ~ 0.016 a.u at the DFT optimised geometry . We posit that the increased magnetic anisotropy of 1-Dy is mainly due to the pendant alkene pinning the coordinated ligand into place, though intra-/inter-ligand dispersion force interactions and crystal packing forces both contribute to the more linear N-Dy-N angle seen in the solid-state structure.