Eu (fod) 3
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| Surname | Eu (fod) 3 | ||||||||||||||||||
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| Molecular formula | C 30 H 30 EuF 21 O 6 | ||||||||||||||||||
| Brief description |
light yellow solid |
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| Molar mass | 1037.49 g mol −1 | ||||||||||||||||||
| Physical state |
firmly |
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| Melting point |
203-207 ° C |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | |||||||||||||||||||
Eu (fod) 3 (EuFOD) is a chemical compound with the empirical formula Eu (OCC (CH 3 ) 3 CHCOC 3 F 7 ) 3 . This coordination compound is primarily in the NMR spectroscopy used to shift signals ( shifting ). It is one of the most well-known lanthanide shift reagents and was particularly popular in the 1970s and 1980s. It was first used by Rondeau and Sievers in 1971 and was the first fluorinated shift reagent.
Structure and reactivity
Eu (fod) 3 consists of three bidentate fod ligands that bind to an Eu (III) center. The 1,1,1,2,2,3,3-hepta f luor-7,7-dimethyl-4,6- o ctan d Ionat (fod) is derived from the acetylacetonate from. Like the structurally related Eu (dmp) 3 , it has a tert- butyl group and a perfluorinated propyl residue. The metal atom has the electron configuration f 6 . The six electrons are unpaired - each is in a different singly occupied f orbital - which results in a pronounced paramagnetism of the complex. The complex is a Lewis acid and can increase its coordination number from 6 to 8. The compound has a high affinity for hard Lewis bases , such as oxygen atoms in ethers and nitrogen atoms in amines . Eu (fod) 3 is soluble in non-polar solvents and shows an increased solubility in comparison with europium complexes with acetylacetone and hexafluoroacetylacetone .
use
NMR shift reagent
The original application of Eu (fod) 3 was to study diastereomeric compounds in NMR spectroscopy. It induces a chemical shift typical of paramagnetic compounds . This shift is more pronounced for protons near the Lewis basic center. This change makes it possible to separate poorly resolved signals. Only small amounts of the shift reagent are used, since the paramagnetism of the compound otherwise leads to a shortened spin-lattice relaxation time and the signals are broadened and the resolution is reduced. The need for shift reagents has decreased due to the availability of spectrometers with higher magnetic fields and the associated increased resolution.
Lewis acid
Eu (fod) 3 can be used as a Lewis acidic catalyst in organic syntheses such as stereoselective Diels – Alder and aldol additions . For example, Eu (fod) 3 can catalyze the cyclocondensation of substituted dienes with aromatic and aliphatic aldehydes to form dihydropyrans and shows a high selectivity for the endo product.
Individual evidence
- ↑ a b c d Resolve-Al ™ EuFOD data sheet at Sigma-Aldrich , accessed on January 24, 2020 ( PDF ).
- ^ Robert E. Sievers, Roger E. Rondeau: New Superior Paramagnetic Shift Reagents for Nuclear Magnetic Resonance Spectral Clarification . In: Journal of the American Chemical Society . tape 93 , no. 6 , March 1971, p. 1522-1524 , doi : 10.1021 / ja00735a049 .
- ↑ Wenzel, TJ; Ciak, JM; Europium, tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedianato) , in: Encyclopedia of Reagents for Organic Synthesis , 2004. John Wiley & Sons, Ltd . ( doi : 10.1002 / 047084289X.rn00449 ).