Lanthanum triiodide

LANTHANUM TRIIODIDE (AND OTHER RARE EARTH METAL TRIIODIDES)... 

Lanthanum triiodide may be obtained from the oxide by a number of routes, such as dissolution of the oxide in Hl(aq) followed by precipitation of the... 

Treating the oxide, trichloride, or metal with boron tribromide or boron triiodide has produced tribromides and triiodides for lanthanum (119). Presumably, treating the metal or the oxide with boron trichloride will produce the trichloride. 

Mattausch, H. et al Angew. Chem. (Int.), 1998, 37(4), 499 The MISi compounds of Lanthanum, Cerium and Praseodymium, and two slightly less iodinated lanthanum derivatives were prepared by fusing stoichiometric mixtures of the triiodides, the metal and silicon. They ignite violently on contact with water. 

CaCl2 Calcium dichloride Calcium(II) chloride 9. La(I3)3 Lanthanum tris(triiodide) Lanthanum(III ) ftriiodide)... 

Lanthanum and cerium triiodide, Lais and Cels, when reduced with strontium or barium or with the pseudo alkaline-earth metals neodymiiun, samarium, and emopium, yield ARl4-type iodides, A = Sr, Ba, Nd, Sm, Eu R = La, Ce. These are built from square-antiprismatic [Mis] polyhedra sharing common faces to columns running parallel [100] (Figure 9). Although these iodides have one excess electron per formula unit, e.g., (Ba +)(La +)(e )(I )4,... 

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... 

The calculated barrier to the transition from a pyramidal to a planar configuration and in the opposite direction is very low and varies depending on the calculation procedure. In particular, according to Vetere et al. (2000), the DFT/PBEO procedure yields barrier values of 0.71, 0.33, 0.08, and 0.04 kj/mol for lanthanum trihalides from trifluoride to triiodide, respectively. Of greater importance is another conclusion made by Kovacs et al. (1997) and substantiated by theoretical calculations in more recent works. The low out-of-plane bending vibrational frequencies V2 obtained in calculations are caused by the use of the harmonic approximation. In reality, these vibrations are anharmonic, and the V2 values are much higher. Unfortunately, taking into account anharmonic effects is currently impracticable for lanthanide trichlorides. 

The triiodides of lanthanum through neodymium possess the orthorhombic PuBrj-type structure (CM = 8), while the triiodides of samarium to lutetium and those of scandium and yttrium possess the hexagonal Bilj-type structure (CN = 6). 

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