Ytterbium(III) chloride

Ytterbium(III) chloride
IUPAC name Ytterbium(III) chloride
Identifiers
CAS number	10361-91-8
ChemSpider	55430 Y
Jmol-3D images	Image 1
SMILES Cl[Yb](Cl)Cl
InChI InChI=1S/3ClH.Yb/h3*1H;/q;;;+3/p-3 Y Key: CKLHRQNQYIJFFX-UHFFFAOYSA-K Y InChI=1/3ClH.Yb/h3*1H;/q;;;+3/p-3 Key: CKLHRQNQYIJFFX-DFZHHIFOAT
Properties
Molecular formula	YbCl3
Molar mass	279.40 g/mol
Appearance	White powder
Density	4.06 g/cm3 (solid)
Melting point	703 °C [1]
Boiling point	1900 °C [1]
Solubility in water	0.17 g/ml (25 °C)
Structure
Crystal structure	Monoclinic, mS16
Space group	C12/m1, No. 12
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y chloride (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Ytterbium(III) chloride is an inorganic chemical compound.

History

Ytterbium, a Lanthanide series element, was discovered in 1878 by Marignac who named the element after a town (Ytterby) in Sweden.^[2] The first synthesis of YbCl₃ in the literature was that of Hoogschagen, in 1946.^[3] YbCl₃ is now a commercially available source of Yb³⁺ ions and therefore of significant chemical interest.

Chemical Properties

The valence electron configuration of Yb⁺³ (from YbCl₃) is 4f¹³5s²5p⁶, which has crucial implications in chemical behavior of Yb⁺³. Also, the size of Yb⁺³ governs it’s catalytic behavior and biological applications. For example, while both Ce⁺³ and Yb⁺³ have a single unpaired f electron, Ce⁺³ is much larger than Yb⁺³ because Lanthanides become much smaller with increasing effective nuclear charge since f electrons are not well shielded, compared to d electrons.^[2] This behavior is known as the Lanthanide contraction. The small size of Yb⁺³ produces fast catalytic behavior and an atomic radius (0.99 Å) comparable to many important biological ions.^[2]

The thermodynamic properties tabulated herein were difficult to obtain since many of the measurements were made in the gas phase where YbCl₃ can exist as ([YbCl₆]^-3)^[4] or Yb₂Cl₆.^[5] The Yb₂Cl₆ species was detected by electron impact (EI) mass spectrometry as (Yb₂Cl₅⁺).^[5] Additional complications in obtaining experimental data arise from the myriad of low-lying f-d and f-f electronic transitions.^[6] Despite these issues, the thermodynamic properties of YbCl₃ have been obtained and the C_3V symmetry group has been assigned based upon the four active infrared vibrations.^[6]

Preparation

YbCl₃ is prepared from Yb₂O₃ with either carbon tetrachloride^[7], or hot hydrochloric acid.^[8]

In practice there are better ways to prepare YbCl₃ for lab use. The aqueous HCl/ammonium chloride route is unsophisticated but very effective. Alternatively hydrated YbCl₃ may be dehydrated using a variety of reagents, particularly trimethylsilyl chloride. Other methods have been published including reacting the finely powdered metal with mercuric chloride at high temperature in a sealed tube. A variety of routes to solvated YbCl₃ have been reported including reaction of the metal with various halocarbons in the present of a donor solvent such as THF, or dehydration of the hydrated chloride using trimethylsilyl or thionyl chloride, again in a solvent such as THF.

Uses

Catalysis

YbCl₃, with a single unpairedf electron, acts as a Lewis acid in order to fill the 4f orbital. The Lewis acidic nature of YbCl₃ allows YbCl₃ to coordinate (usually as [YbCl₂]⁺) in transition states to catalyze alkylation reactions, such as the aldol reaction^[9] and the Pictet-Spengler reaction.^[10]

Aldol reaction

The aldol reaction is a versatile reaction in synthetic organic chemistry. YbCl₃ serves a Lewis acid catalyst which aids the Pd(0) catalyzed decarboxylative aldol reaction between a ketone enolate and an aldehyde. Transition states A and B show the coordination method of the ytterbium salt as a Lewis acid.^[9] For the depicted decarboxylative Aldol reaction with R = tert-butyl and R’ = -(CH₂)₂Ph, the reaction yields show YbCl₃ is an effective Lewis acid catalyst:

Metal salt[9]	% yield of2
FeCl3	40
ZnCl2	68
CuCl2	40
LaCl3	60
YbCl3	93

Pictet-Spengler reaction

The Pictet-Spengler reaction produces a valuable tetrahydro-β-carboline ring system which can be later used for synthetically prepared indole alkaloids.^[10] The Lewis acid catalyzed reaction with YbCl₃ gave excellent yields and reduced reaction times from four days to 24 hours.^[10]

Esterification

The small size of Yb³⁺ provides fast catalysis, but at the cost of selectivity. For example, the mono-acetylation ofmeso-1,2-diols is fastest (2 h) with YbCl₃, but chemoselectivity for the mono-acetylated product is low (50%) compared to CeCl₃ (23 h, 85%).^[11]

Acetalisation

Ytterbium(III) chloride is a powerful catalyst for the formation of acetals using trimethyl orthoformate.^[12] In comparison with cerium(III) chloride and erbium(III) chloride, the ytterbium salt was found to be the most effective. Excellent yields are obtained from a variety of aldehydes within a few minutes at room temperature, as in the example above involving an acid-sensitive aldehyde.

Biology

YbCl₃ is a NMR shift reagent that produces different resonances with nuclei in contact with the YbCl₃ versus those nuclei not in contact with the shift reagent.^[13] Generally paramagnetic species, such as a (Lanthanide)⁺³ ion, are desirable shift reagents.^[13] Membrane biology has been greatly influenced by YbCl₃, where³⁹K⁺ and²³Na⁺ ion movement is critical in establishing electrochemical gradients.^[13] Nerve signaling is a fundamental aspect of life that may be probed with YbCl₃ using NMR techniques. YbCl₃ may also be used as a calcium ion probe, in a fashion similar to a sodium ion probe.^[14]

YbCl₃ is also used to track digestion in animals. Certain additives to swine feed, such as probiotics, may be added to either solid feed or drinking liquids. YbCl₃ travels with the solid food and therefore helps determine which food phase is ideal to incorporate the food additive.^[15] The YbCl₃ concentration is quantified from ICP (inductively coupled plasma) mass spectrometry to within 0.0009 μg/mL.^[2] YbCl₃ concentration versus time yields the flow rate of solid particulates in the animal’s digestion. The animal is not harmed by the YbCl₃ since YbCl₃ is simply excreted in fecal matter and no change in body weight, organ weight, or hematocrit levels has been observed in mice.^[14]

The catalytic nature of YbCl₃ also has an application in DNA microarrays, or so called DNA “chips”.^[16] YbCl₃ led to a 50-80 fold increase in flourescein incorporation into target DNA, which could revolutionize infectious disease detection (such as a rapid test for tuberculosis).^[16]

References

1. ^ ^{a b} Walter Benenson, John W. Harris, Horst Stöcker (Springer). Handbook of Physics. Springer. p. 781. ISBN 0387952691. http://books.google.com/?id=RbLE77b6eRUC&pg=PA781. 
2. ^ ^{a b c d} Evans, C.H. Biochemistry of the Lanthanides; Plenum: New York, 1990.
3. ^ Hoogschagen, J. Pysica 1946, 11(6), 513-517.
4. ^ Gau, W.J.; Sun, I.W. J. Electrochem. Soc. 1996, 143(1), 170-174.
5. ^ ^{a b} Chervonnyi, A.D.; Chervonnaya, N.A. Russ. J. Inorg. Chem. (Engl. Transl.) 2004, 49(12), 1889–1897.
6. ^ ^{a b} Zasorin, E.Z. Russ. J. Phys. Chem. (Engl. Transl.) 1988, 62(4), 441-447.
7. ^ Goryushkin, V.F.; Zalymova, S.A.; Poshevneva, A.I. Russ. J. Inorg. Chem. (Engl. Transl.) 1990, 35(12), 1749–1752.
8. ^ Jörg, S.; Seifert, H.J. Termochim. Acta 1998, 318, 29-37.
9. ^ ^{a b c} Lou, S.; Westbrook, J.A.; Schaus, S.E. J. Am. Chem. Soc. 2004, 126, 11440-11441.
10. ^ ^{a b c} Srinivasan, N.; Ganesan, A. Chem. Commun. 2003, 916-917.
11. ^ Clarke, P.A. Tetrahedron Lett. 2002, 43, 4761-4763.
12. ^ Luche, Jean-Louis; Gemal, André Luis (1978). "Efficient synthesis of acetals catalysed by rare earth chlorides". Journal of the Chemical Society, Chemical Communications 1978 (22): 976–977. doi:10.1039/c39780000976. http://xlink.rsc.org/?doi=C39780000976 
13. ^ ^{a b c} Hayer, M.K.; Riddell, F.G. Inorg. Chim. Acta 1984, 92, L37-L39.
14. ^ ^{a b} Shinohara, A.; Chiba, M.; Inaba, Y. J. Alloys Cmpds. 2006, 408-412, 405-408.
15. ^ Ohashi, Y.; Umesaki, Y.; Ushida, K. Int. J. Food Micro. 2004, 96, 61-66.
16. ^ ^{a b} Browne, K.A. J. Am. Chem. Soc. 2002, 124, 7950-7962.