Lutetium halides

Ylide derivatives of lutetium with high thermal stability are obtained using pentamethylcyclopentadienyl lutetium halides as starting materials (Schumann et al., 1984d) ... 

Metathetical routes using bulky lithium guanidinates as starting materials have also been employed to synthesize bis(guanidinato) lanthanide halides as well as reactive alkyls and hydrides. Scheme 63 shows as a typical example the formation of the lutetium chloro precursor, which was isolated in 76% yield. ... 

Lawrencium is the last of the transuranic elements and the 15 th in the actinide series (there are 15 elements in the lanthanide series as well, assuming you start counting the series at the elements lanthanide and actinium, respectively.) It is assumed that lawrencium has some chemical and physical characteristics similar to lutetium, located just above it in the lanthanide series. It is also located at the bottom of the group 17 (VILA) elements, which makes it the heaviest of the halides. 

In this article, we will begin with an overview of the structures of binary rare-earth halides, RXz (with R being a cation of a rare-earth element, scandium, yttrium, lanthanum and cerium through lutetium and X a halide ion). Because binary halides were the subject of several excellent reviews, also in this handbook (Haschke 1979, Eick 1994), they will be mentioned only briefly. 

Marked differences are observed between the properties of the halides. The trifluorides are stable in air at room temperature and are non-hydroscopic. They are sparingly soluble in water with solubility product constants which vary from 10 for lanthanum to 10 for lutetium (DaDilva and Queimado, 1973). In liquid HF, the solubilities are less than 4x 10 mole/ (Ikrami et al., 1972). At high temperatures the trifluorides react with oxygen and moisture to form the oxide fluorides, ROF, which are stable in air at temperatures greater than 1000°C. Conversion of the fluorides to the oxides may be achieved by heating in steam at 1000°C (Stezowski and Eick, 1970). 

In contrast, the anhydrous trichlorides, tribromides and triiodides and the reduced halides are extremely air sensitive materials and are rapidly hydrated or hydrolyzed in air. The triiodides are especially moisture sensitive and deliquesce. Unlike the trifluorides, the other trihalides are very soluble in water at 25°C. Solubilities of the trichlorides vary from 3.89 moles/ for lanthanum, to a minimum of 3.57 moles/ at terbium and back up to 4.10moles/ at lutetium with pH values of the saturated solutions in the range 1.0-2.0 (Spedding et al., 1974a). At high temperatures, the trichlorides, tribromides and triiodides also... 

Dehydration of the dehydrated trihalides is a final method for oxide conversion. The hydrated trichlorides, tribromides and triiodides, RXj- H20, are obtained by dissolution of the oxides in aqueous hydrohalic acid and condensation by warming and desiccation (Ashcroft and Mortimer, 1968 Brown et al., 1968). The hydrated trifluorides are prepared by dissolution of the oxide in HNO3 or HCl and precipitation with aqueous HF. The filtered trifluoride may be dehydrated by heating slowly to 600°C in an inert gas stream or in vacuum (Strizhkov et al., 1972). Products obtained by heating in air are contaminated with oxide fluoride (Batsanova, 1971). Thermal decomposition studies of the hydrated trichlorides, cf. section 5.1, have shown that the oxide chlorides are readily formed, but careful dehydration under N2 flow has apparently been successful for the chlorides (Ashcroft and Mortimer, 1968). Tribromides have also been prepared by careful vacuum dehydration, but the lutetium products were contaminated with oxide bromide (Brown et al., 1968). In general simple dehydration becomes increasingly difficult with increasing atomic number of both the lanthanide and the halide. 

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