Lanthanide Nitrate Complexes of Tri-Isobutylphosphine Oxide: Solid State and CD₂Cl₂ Solution Structures

Abstract

The complexes Ln(NO(3))(3)L(3) between Ln(NO(3))(3) and (i)Bu(3)PO (=L) have been prepared for Ln = La-Lu (excluding Pm). The isolated complexes have been characterized by infrared spectroscopy, mass spectrometry, and elemental analysis. The single crystal X-ray structures have been determined for representative complexes across the series Ln = Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er, Tm, and Yb and show the coordination geometry around the metal to be the same with 9-coordinate lanthanide ions and bidentate nitrates. Subtle changes in the coordination of the nitrate ligand occur from Sm onward. Changes in the infrared spectra correlate well with changes in the X-ray structures. Solution properties have been examined by variable temperature multinuclear ((1)H, (13)C, (15)N, and (31)P) NMR spectroscopy in CD(2)Cl(2). The spectra of complexes of the early lanthanides are consistent with the presence of a single species in solution while those of the heavier lanthanides show that more than one complex is present in solution and that two inequivalent phosphorus environments are observable at low temperature. The fluxional behavior is lanthanide dependent with smaller ions giving static structures at higher temperature. Complexes with tricyclohexylphosphine oxide show that the dynamic NMR behavior is also related to the size of the ligand. Analysis of the lanthanide induced shifts indicates minor changes in solution structure occur from Sm onward which correlate well with the solid state structures.

Separation of rare-earth ions from ethylene glycol (+LiCl) solutions by non-aqueous solvent extraction with Cyanex 923

“…Unfortunately, any t, including the two-, three-and four-legged scattering paths resulted in bad ts of this peak which might be due to highly distorted paths lengths. 47,48 The best t was obtained by including only the two-legged scattering path Ln-P. This resulted in a coordination number of 4.5(4), a DebyeWaller factor of 0.01(1)Å 2 and a path length of 3.788(7)Å.…”

Complexes of lanthanide chlorides with tricyclohexylphosphine oxide. The single crystal X-ray structures and solution properties of pentagonal bipyramidal complexes [Ln(H2O)5(Cy3PO)2]3+·Cy3PO·3Cl− Ln=Dy, Er

“…4 The single crystal X-ray structures and solution properties of pentagonal 5 bipyramidal complexes [Ln(H 2 O) 5 a b s t r a c t 24 The products of the reactions of tricyclohexlyphosphine oxide, Cy 3 PO = L, with lanthanide chlorides 25 (Ln = La, Dy, Er, Yb) have been investigated by solution NMR spectroscopy and single crystal X-ray crys- 26 tallography (Dy, Er). The structures of the complexes are based on a pentagonal bipyramidal arrangement 27 around the central Ln 3+ ion with two Cy 3 PO in axial positions and five water molecules in the equatorial 28 plane with molecular formulae LnL n (H 2 O) 5 ÁLÁ3ClÁH 2 OÁEtOH.…”

The interactions between the sterically demanding trimesitylphosphine oxide and trimesityphosphine with scandium and selected lanthanide ions

“…It is interesting that the temperature dependence in the Mes3PO / Ln 3+ systems is opposite of that found for 31-P shift for phosphine oxides directly bonded to lanthanides [7,8], but the same as for phosphine oxides hydrogen bonded to lanthanide coordinated water molecules. In the absence of crystallographic data from isolated compounds it is not possible to be certain of the nature of this interaction, but hydrogen bonding to the coordinated water molecules, as previously observed with other sterically crowded phosphine oxides [11,12] seems reasonable.…”

“…We have previously studied the effect on structures and solution properties of increasing the size of the R group in R3PO where we found that solid state structures and solution properties depend on a balance between steric and electronic effects of the phosphine oxides and the size of the lanthanide ions [6][7][8]. Cone angles, are not available for phosphine oxides, and as a result we have used the cone angles of the parent phosphine [9] as a proxy for the steric demands of the oxides.…”

“…Cone angles, are not available for phosphine oxides, and as a result we have used the cone angles of the parent phosphine [9] as a proxy for the steric demands of the oxides. Previous studies on trialkyl phosphine oxides R3PO (R = Et [6], i Bu [7], cyclohexyl [10] and t Bu [8])…”