Correlation of optical and NMR spectral information with coordination variation for axially symmetric macrocyclic Eu(iii) and Yb(iii) complexes: axial donor polarisability determines ligand field and cation donor preference

摘要: In Bleaney's theory of magnetic anisotropy, the second-order crystal field coefficient, Bo2, is predicted to determine dipolar NMR shift paramagnetic lanthanide complexes in solution. This parameter has been measured directly, by analysing europium emission spectra for a series eight- and nine-coordinate axially symmetric based on cyclen including aza-carboxylate ligands (e.g. DOTA), phosphonates (DOTP), phosphinates several carboxamides DOTAM). For both Yb Eu with common coordination number geometry (square antiprism (SAP) or twisted square (TSAP)), correlates very well this parameter, which also determines sign magnitude major CD band near-IR enantiopure complexes. Measurements free energy change associated axial ligand exchange cationic tetraamide complex, [Eu(DOTAMPh)](CF3SO3)3 supported simple electrostatic perturbation model, have interpreted terms predominant donor atom polarisation model affords assessment Ln ion preference ranks coefficient.