Structural diversity in the series of lanthanide complexes [Ln(Ph3PO)n(NCS)3] (n = 3, 4)

Lawrence Chan, Simon A. Cotton, Joanna Dickson (nee Harris), Andrew W.G. Platt, Paul R. Raithby, Stefanie Schiffers, Alexander Tait, John E. Warren

Research output: Contribution to journalArticlepeer-review


Two unique series of lanthanide complexes [Ln(Ph3PO)4(NCS)3] (Ln = La-Tb, except Pm) and [Ln(Ph3PO)3(NCS)3] (Ln = Sm-Lu, Y) have been structurally characterised. The isomorphous series [Ln(Ph3PO)4(NCS)3] crystallises in the monoclinic centrosymmetric space group P21/c, and the metals display a capped octahedral coordination geometry. In contrast, the isomorphous series [Ln(Ph3PO)3(NCS)3] (Ln = Sm-Lu, Y) crystallise in the non-centrosymmetric space group R3, with the metal displaying an octahedral coordination geometry; the fac-isomer being observed in all cases. Intriguingly, for the metals Sm-Tb both the seven and six coordinate complexes can be isolated from the respective synthetic routes suggesting a structural equilibrium in solution. An analysis of the distortions of the ligand polyhedron in the two series using the continuous shape measurement (CShMs) method suggests trends across the series relating to the fit of the ligands with the size of the lanthanide ions.

Original languageEnglish
Article number115826
Early online date4 Apr 2022
Publication statusPublished - 1 Jul 2022


  • Crystal structures
  • Lanthanide contraction
  • Lanthanides
  • Phosphine oxide
  • Thiocyanate


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