Multi-configurational electronic structure theory calculations were performed on 1-Ce, 1-Pr, 1-Nd and 1-Sm in OpenMolcas version 23.02. The molecular geometries from single crystal XRD structures were used with no optimization, selecting a single molecule from the asymmetric unit and For pNMR calculations, a temperature of 297 K was used for all analysis, and shifts were averaged over all atoms in each environment. An ANO-RCC-VTZP basis set was employed for the lanthanide ion, an ANO-RCC-VDZP basis set for the ligand atoms directly coordinated to the lanthanide ion and an ANO-RCC-VDZ basis set for all other atoms. 112 Two-electron integrals were decomposed using the Cholesky method with a threshold of 10 -8 . The PCM solvent model 113 was used for some calculations using the magnetic susceptibility method 81 but was found to have an insignificant effect (Table ). Geometry optimizations for 1-Ln were carried out in Gaussian 16 114 using density functional theory, starting from XRD structures. These used the PBE exchange-correlation functional 115 with the GD3 dispersion correction and a cc-pVDZ basis set. An f-in-core pseudopotential was used for the lanthanide ion. 117 Calculated shifts for the XRD and optimized geometries, found using the magnetic susceptibility method, are compared in Table . These differed, but neither gave reliably better agreement with experiment than the other. The XRD structures were used for all further calculations.