Synthesis, Structural Characterisation and Solution Behaviour of High‐Symmetry Lanthanide Triflate Complexes with the Sterically Demanding Phosphine Oxides Cy₃PO and tBu₃PO

Abstract

The synthesis and characterisation of complexes formed from lanthanide trifluoromethanesulfonates [Ln(OTf)3] and tricyclohexylphosphine oxide (Cy3PO) or tri‐tert‐butylphosphine oxide (tBu3PO) are described. The structures of [Ln(H2O)5(Cy3PO)2]·2R3PO·(OTf)3 (Ln = Pr, Tm; R = Cy and Ln = Nd; R = tBu) are pentagonal bipyramidal with an equatorial plane of five H2O ligands and two axial Cy3PO ligands. The remaining Cy3PO molecules are H‐bonded to the coordinated water molecules, as are the triflate anions. NMR spectroscopy showed that the triflate ions remain associated with the complexes in CDCl3 solution. Lanthanide‐induced shifts in the 19F and 31P NMR spectra confirm that one structure is present for all the lanthanides with an additional structure for the heavier metals. The acidity of the complexes was examined by 31P NMR spectroscopic studies on the reactions between [Ln(H2O)5(Cy3PO)2]·2Cy3PO·(OTf)3 (Ln = La, Eu, Er, Lu) and phosphines PR3 (R = Ph, mesityl, Cy), Ph2PC2H4PPh2 and Ph2PC3H6PPh2. Protonation of the more basic phosphines and H‐bonding to the less basic phosphines is observed.

Probing a variation of the inverse-trans-influence in americium and lanthanide tribromide tris(tricyclohexylphosphine oxide) complexes

“…† While not ideal, these results, particularly in CD 2 Cl 2 show that at low temperature a static mer-octahedral environment is present, similar to the crystal structure, and corroborating earlier studies with these LnBr 3 (OPcy 3 ) 3 complexes. 57,[90][91][92] Theoretical analysis…”

Lanthanide tri- and tetrathionates and their complexes with triphenylphosphine oxide

“…The Nd and three sulfur atoms are coplanar with the coordinated oxygen atoms lying on average 1.03 Å above and below this plane, such that the 6-membered ring adopts a chair configuration. [X]3 X = CF3SO3 [25], Cl [26,27] and Br [26,28].…”