Lutetium compounds

Table 1 lists the lattice parameters of the RxTyPbz plumbides in the order of the periodic table, i.e. from the yttrium to the lutetium compounds. For each compound also the structure type is listed. 

Gadolinium texaphyrin (Gd-tex Figure 4.8) is reported to be an effective radiation sensitizer for tumour cells, whilst the corresponding lutetium compound, which absorbs light in the far-red end of the visible spectrum, is in Phase II trials for photodynamic therapy for brain tumours and breast cancer. 

The organometallic chemistry of scandium is generally similar to that of the later lanthanides. It thus forms a cyclopentadienyl ScCps that has mixed mono- and pentahapto-coordination like LuCps. An anionic methyl [Li(tmed)]3[M(CH3)6] is formed by scandium, as by the lanthanides. However, there are often subtle differences that should be borne in mind. The pentamethylcyclopentadienyl compound [ScCp 2Me] is a monomer but the lutetium compound is an asymmetric dimer [Cp 2Lu(/u.-Me)LuCp 2Me]. Similarly, whilst triphenylscandium is obtained as a bis(thf) adduct, [ScPh3(thf)2], which has a TBPY structure with axial thf molecules, the later lanthanides form octahedral [LnPh3(thf)3]. Triphenylscandium and the phenyls of the later lanthanides are made by different routes. 

Figure 1 displays the plots of the TCATC/G quantity as a function of ATC derived from our experimental results for the R2Fei4B compounds and their hydrides. The data for the lutetium compounds (TCo = 535 K for Lu2Fei4B and Tco = 620 K for Lu2Fe14BH2 5) have been adopted as a TCo- It is known that the 4f electron shell of the Lu3+ (4f14) - ion has no magnetic moment. Therefore, in our case, the Lu compound models the iron sublattice magnetization for the whole series of R-Fe compounds under consideration. 

Eanthanide triflates reacts with PhsPO in ethanol forming [En(OTf)2(Ph3PO)4] OTf (Ln = La, Nd, Er, Lu). The erbium and lutetium compounds have octahedral coordination, with monodentate triflates, but the complexes of the larger La and Nd have seven-coordination with one triflate being bidentate. 

The first structure of a [Ln(phen)2(N03)3] complex was reported in 1992 for the lanthanum compound.It closely resembled the established bipy analogue in that the three nitrate groups were bidentate and the lanthanum was 10-coordinate. The structural information was complemented by a multinuclear solution ( H-, C-, O-, and La) NMR study. The structure of the other extreme member of the series, the lutetium complex, was reported in 1996. Unlike the La complex, but like [Lu(bipy)2(N03)3], the study was not complicated by disorder. The complexes appear to form an isomorpohous and isostructural series. On moving from the lanthanum to the lutetium compound, the Ln—N distances decrease from 2.646(3)-2.701(3) A (La) to 2.462(8)-2.479(8) A (Lu), and the range of Ln—O distances decreases from 2.580(3)-2.611(3) A for the lanthanum compound to 2.364(8)-2.525(6) A for the lutetium complex. Several structures have subsequently been reported of other [Ln(phen)2(N03)3] systems. [Ln(phen)2(N03)3] (Ln = Pr, Lu, Dy, are isostructural the individual complex... 

The lutetium hahdes (except the fluoride), together with the nitrates, perchlorates, and acetates, are soluble in water. The hydroxide oxide, carbonate, oxalate, and phosphate compotmds are insoluble. Lutetium compounds are all colorless in the solid state and in solution. Due to its closed electronic configuration (4f " ), lutetium has no absorption bands and does not emit radiation. For these reasons it does not have any magnetic or optical importance, see also Cerium Dysprosium Erbium Europium Gadolinium Holmium Lanthanum Neodymium Praseodymium Promethium Samarium Terbium Ytterbium. 

Figure 3 shows the XRD pattern of the precursor powders obtained at different pH values. For the precursor prepared at pH=5.5 and 6, nearly identical patterns were observed. The precursors obtained at pH=7, and 8, on the other hand, show quite different XRD patterns in comparison with those of lower pH values. All these patterns could not be indexed to known lutetium compound, which means that the lutetium compounds prepared by our method are new phases that have not been reported in the data-base of JCPDS. Due to limited literature for the lutetium compounds, we cannot decide the definite composition of the precursors at this time. 

The first definitive compound of this class, tetrakis(tetrahydrofurane) lithium tetrakis(2,6-dimethylphenyl) lutetiate has been prepared by the action of 2,6-dimeth-ylphenyl lithium with anhydrous lutetium trichloride in tetrahydrofurane at — 78°C, following by repeated concentration, filtration, and redissolution in tetrahydrofurane. This procedure ultimately gave, on addition of benzene, colorless needles. X-ray diffraction shows the lutetium atom to be bound to four V-aryl groups in an approximately tetrahedral array the four Lu-C distances are 2.425 A, 2.439 A, 2.442 A and 2.501 A. The four Lu-Cl-C4 angles deviate somewhat from 180° (see fig. 30), taking values from 175.6° to 167.7° the six C-Lu-C angles around lutetium are 99.4°, 101.2°, 111.0°, 112.4°, 115.5° and 118.2°. The analogous ytterbium compound has been similarly prepared and is isostructural. It smoulders instantly on exposure to air while the lutetium compound appears less readily affected (S.A. Cotton et al., 1972). 

The reactions of LnCls with only one equivalent of K2C8H8, carried out in THF, afford complexes of the type [C8H8LnCl(THF)2]2 (105,111, 112). The investigation of the structure of the cerium complex proves the dimeric nature and shows the two cerium atoms bridged asymmetrically by the two chlorine atoms,and, in each case, coordinated by one cyclooctatetraenyl ring and two THF molecules (113). The complexes loose THF upon heating to 60 C in vacuo. The lutetium compound reacts with alkyl-lithium compounds with formation of the first cyclooctatetraenyl(organ-yl)lutetium compounds (11 ) ... 

Pentamethylcyclopentadienyl derivatives of Sc (58) and Lu (85,86, 87) have also been prepared and investigated. The nmr spectra suggest an equilibrium between the monomeric and the dimeric species as shown for the lutetium compounds. They catalyze the polymerization of olefins and activate C-H-bonds, even those of tetramethylsilane (85,86,87) ... 

When the scandium and lutetium compounds are triturated with toluene, one THE molecule is lost, resulting in [Ln(CH2Ph)3(THE)2] (Ln = Sc, Lu) of which the scandium compound has a trigonal bipyramidal structure. There is no evidence for [Yb(Bz)3(THF)3] when C6H5CH2K reacts with [Ybl3(THF)3], the mixed-valence compound [Yb°(CH2Ph)(THF)5]+ [Yb (CH2Ph)4(THF)2]- results As a family of a-alkyls obtainable for most lanthanides, the benzyls have promise as synthetic precursors, notably for phosphorus-stabilized carbenes. ... 

An American chemist, Theodore William Richards, had made it his mission in Hfe to make very careful atomic weight determinations. In 1911 he performed 15 000 re-crystallizahons of lutetium bromide, obtaining a very pure lutetium compound that made an accurate atomic weight determination possible. 

The reliability of measurements of the partial pressures of R2CI6 can in principle be verified by a standard procedure based on changes in the thermod)mamic characteristics of these molecules along the lanthanide series. However, the enthalpy of atomization AatH°(298) is not the most convenient parameter for such a check since it does not vary monotoni-cally with the number of the lanthanides in the series. The plot of this dependence is a broken line with maxima at lanthanum, gadolinium, and lutetium compounds and minima at europium and ytterbium compounds. In addition, the enthalpy of atomization usually increases in going from dysprosium to erbium dimers. 

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