). All 1-Ln are isostructural and isomorphous, subject to minor variations in structural metrics, so we restrict our discussion to the dataset of 1-Dy; we do not comment further on the structures of 2-Ln, which show similar metrical parameters to other rare earth allyl complexes . The solid-state structures of 1-Ln exhibit significant disorder and each dataset was modelled as two components, 1-Ln-A and 1-Ln-B, which were competitively refined (for 1-Dy we find a 0.649(5):0.351(5) ratio of 1-Dy-A:1-Dy-B). We therefore do not make firm conclusions on the significance of individual metrical parameters as a range of values will be present in crystalline material. Powder XRD patterns for 1-Ln are consistent with each other and single crystal data; Le Bail profile analysis indicates high phase purity in all cases (Figures S22-S25) .