Low co-ordination numbers in lanthanide and actinide compounds. Part I. The preparation and characterization of tris{bis(trimethylsilyl)-amido}lanthanides

Abstract

The new three-co-ordinated lanthanide complexes [Ln{N(SiMe,),),],where Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Ho, Yb, and Lu, and [Y{N(SirneJ2),], have been prepared and their l H n.m.r. and electronic spectra are reported and discussed. The magnetic susceptibility of the Gd complex a t 98 and 298 K is reported.College, Mile End Road, London E l 4NS THE chemistry of the lanthanide elements is characterized by a tendency to exhibit high co-ordination numbers (Le. >6) in their compounds, which are predominantly ionic in nature, Typical co-ordination numbers for these large ions are 8, 9, and 10, though 6, 7 , and 12 are also known. Even six-co-ordination, so common for &transition metals, is quite rare for lanthanides; an example is provided by the hexahalide complex [LnXJ3-(X = C1, Br, or I ) . l 7 , Co-ordination polyhedra are often of quite low symmetry, which hinders interpretation of electronic spectra, though Oh six-coordination , D,, nine-co-ordination , and near-lh twelveco-ordination are known.Recent X-ray crystallographic work has shown that the tris(bis(trimethylsilyl)amido}chromium and iron compounds [M(N(SiMe,),},] (I) (M = Cr or Fe), originally prepared by Burger and Wannagat: are authentic three-co-ordinated complexes with D, molecular symmetry. Other transition metal derivatives (I; M = Sc, Ti, or V) have since been isolated5 and crystal-field cause they might have low and (for these elements) otherwise unknown co-ordination numbers. Reaction (1) involving the anhydrous lanthanide chloride and the LnCl, + 3LiN(SiMe,), ---+ theoretical amount of LiN(SiMe,), proved successful * and we now present a full account of the preparation and properties of a number of three-co-ordinated lanthanide complexes (I; M = La, Ce, Pr, Nd, Sm, Eu, Gd, Ho, Yb, and Lu) and the corresponding yttrium complex.The new compounds are readily hydrolysed, soluble in organic solvents, and crystallize as needles from pentane. The cerium compound is exceedingly readily oxidised by even minute traces of air. The m.p.s all lie within the range 149-170

Near-IR Two Photon Microscopy Imaging of Silica Nanoparticles Functionalized with Isolated Sensitized Yb(III) Centers

“…were synthesized modifying a procedure reported in literature. 71 Silica (AEROSIL 200 m 2 /g) was dehydroxylated according a published procedure. 72 All infrared (IR) spectra were recorded using a Bruker α spectrometer placed in the glovebox equipped with OPUS software.…”

Synthesis and Optimization of the Sintering Kinetics of Actinide Nitrides

“…In the studies cited above, many lanthanide precursors have been prepared in a rigorously controlled dry oxygen free environment. However, cerium was an exception [104], as it was pointed out by the researchers. The cerium compounds were readily oxidized by even minute traces of air.…”

“…For example, plutonium and uranium nitrides have been directly prepared from the liquid ammonia and the corresponding iodides in liquid ammonia [60,103]. Lanthanide nitride precursors such as Trisbistrimethylsilylamidolanthanides ( (SiMe 3 ) 2 ) 3 ) (where the metals include: La, Ce, Pr, Nd, Sm, Eu, Gd, Ho, Yb, Y and Lu) have been prepared by the reaction between iodides and lithiumhexamehtyldisilazane in THF at room temperature [104]. Lanthanide nitrides such as YN, LaN, PrN, NdN, SmN, EuN, TbN, ErN, and YbN have also been reported to have been prepared by ammonolysis of the aforementioned lanthanide nitride precursors in ammonia gas at high temperature [105].…”

Zur Elektronenstruktur hochsymmetrischer Verbindungen der f-Elemente, XXV / The Electronic Structure of Highly Symmetrical Compounds of thef-Elements, XXV

“…Wir haben sowohl die gemäß der Original vorschrift [1 ] hergestellten unsublimierten Ln(Btmsa)3-Ausgangsverbindungen als auch die nach Umsetzungen erhaltenen Produkte näher analysiert und mußten dabei feststellen, daß je weils auch ein THF-haltiges N ebenprodukt auf trat.…”

“…Es war das Ziel der vorliegenden Arbeit, durch geringfügige Modifizierung der von Bradley et al angegebenen Vorschrift [1] zunächst weitgehend THF-freie polykristalline Ln(Btmsa)3-Komplexe darzustellen und anschließend größere Einkristalle …”