The H-only structural optimization of diamagnetic 1-La, and full geometry optimization of desolvated La(THF)1 and La(THF)0 analogues were performed using ADF 2017; structural optimization of paramagnetic 1-M (where performed) and desolvated M(THF)1 and M(THF)0 analogues were conducted in the gas phase using DFT with Gaussian 16 106 and electron correlation were described using the PBE functional. All central lanthanide atoms were treated with the Stuttgart RSC-ANO ECP basis set, and all remaining atoms with cc-pVDZ. Diamagnetic NMR chemical shifts were computed with ADF 2017. Spin-orbit relativistic, single-point calculations, using the optimized geometries described above, employed either the BP86, PBE0, SAOP or B3LYPHFXX (XX = 10, 15, 20, 25, 30, 35, 40, 45, 50) hybrid functionals. All-electron Slater-type orbital triple-ζ quality basis sets (TZ2P) were employed in conjunction with the two-component zero-order regular approximation (ZORA) Hamiltonian. The Si NMR chemical shifts are reported relative to TMS. Scalar relativistic approaches (spin-orbit neglected) were used within the ZORA Hamiltonian to include relativistic effects, and a benzene solvent continuum was added. The local density approximation (LDA) with a correlation potential was used in all calculations. Generalized gradient approximation corrections were performed using the functionals of Becke and Perdew. 117,118 NBO analysis was carried out using NBO6. QTAIM analysis was performed within the ADF package; the MOs and NBOs were visualized using ADFView.