Samarium spectroscopy

Diorganotin(IV) complexes with 4//-pyrido[l,2-n]pyrimidin-4-ones 109 (96MI4), complexes of 2-methyl- and 2-methyl-8-nitro-9-hydroxy-4//-pyrido[l,2-n]pyrimidin-4-ones with Ag(I), Cu(II), Ni(II), Co(II), and Mn(II) ions (00MI23), 2,4-dimethyl-9-hydroxypyrido[l, 2-n]pyrimidinium perchlorate and its complexes with prasedynium, neodymium, samarium and europium (00MI24) were characterized by UV spectroscopy. 

The (C Me ) Sm(THF) metal vapor product provided the first opportunity ta see if Smdl) complexes (y =3.5—3.8 Ufi) could be characterized by H NMR spectroscopy (24). Fortunately, the paramagnetism doesn t cause large shifting and broadening of the resonances and hence samarium provides the only Ln(III)/Ln(II) couple in which both partners are NMR accessible. Once the existence and identity of (C Mej- SmdHF) was known, a solution synthesis was developed from KC Me and Sml THF) (44). This system is the preferred preparative route and also provides another soluble organosamarium(II) complex, [(C Me )Sm(THF)2(u-I)]2, under appropriate conditions. This is another xample of how solution studies subsequently catch up to the research targets often identified first in metal vapor reactions. 

French chemist who discovered gallium, samarium, and dysprosium, and perfected methods of separating the rare earths He ranks with Bunsen, Kirch-hofiF, and Crookes as one of the founders of the science of spectroscopy. 

Boisbaudran s researches on the rare earths also yielded a rich harvest of results, for he discovered samarium and dysprosium (2). His investigations in the field of spectroscopy were also of high merit... 

Addition of the same NHC to Eu(thd)3 (thd — tetramethylheptanedioate) affords the europium(III) adduct Eu(thd)3(NHC). The europium-NHC bond distance of 2.663(4) A is shorter than that of the samarium(II) complex and is consistent with the higher oxidation state of the lanthanide centre. The yttrium(III) analogue was also prepared and characterised by NMR spectroscopy. The C2 carbon resonates at 199 ppm in the 13C NMR spectrum, with a yc coupling constant of 33 Hz. This indicates that the NHC remains bound to the metal centre in solution and does not dissociate on the NMR timescale. 

Roesky introduced bis(iminophosphorano)methanides to rare earth chemistry with a comprehensive study of trivalent rare earth bis(imino-phosphorano)methanide dichlorides by the synthesis of samarium (51), dysprosium (52), erbium (53), ytterbium (54), lutetium (55), and yttrium (56) derivatives.37 Complexes 51-56 were prepared from the corresponding anhydrous rare earth trichlorides and 7 in THF and 51 and 56 were further derivatised with two equivalents of potassium diphenylamide to produce 57 and 58, respectively.37 Additionally, treatment of 51, 53, and 56 with two equivalents of sodium cyclopentadienyl resulted in the formation of the bis(cyclopentadienly) derivatives 59-61.38 In 51-61 a metal-methanide bond was observed in the solid state, and for 56 this was shown to persist in solution by 13C NMR spectroscopy (8Ch 17.6 ppm, JYc = 3.6 2/py = 89.1 Hz). However, for 61 the NMR data suggested the yttrium-carbon bond was lost in solution. DFT calculations supported the presence of an yttrium-methanide contact in 56 with a calculated shared electron number (SEN) of 0.40 for the yttrium-carbon bond in a monomeric gas phase model of 56 for comparison, the yttrium-nitrogen bond SEN was calculated to be 0.41. 

Reaction of 3 equiv. of 2,6-diisopropylaniline with Sm[N(SiMe3)2]3 affords dimeric [Sm(NHAr)3]2, in which each metal center is engaged in an -arene interaction with the aryl ring of an amide ligand attached to an adjacent samarium. IR spectroscopy indicates that the r-arene interactions are maintained in solution. 

Four binuclear samarium complexes [Sm( x-p-XOBz)2(Tp)]2 have been prepared by the reaction of SmCl3, K(Tp), and sodium p-X-benzoate (X = H, Cl, F, NO2) in 1 1 2 ratio. These complexes have been characterized by elemental analysis, IR spectroscopy, thermogravimetry, optical properties, X-ray, and magnetic measurement studies. The X-ray structure shows that these complexes are isostruc-tural, each samarium being seven-coordinate.627... 

Childs, W. J. Poulsen, 0. and Goodman, L. S., "Laser-rf double-resonance spectroscopy in the samarium I spectrum Hyperfine structure and isotope shifts," Phys. Rev., 1979, 19, 160-167. 

Co-condensates between metallic samarium and 4-pentyl-4 -cyanobiphenyl (5CB) in the solid phase have been obtained via joint atomic/molecular beam deposition on a cooled calcium fluoride surface at liquid nitrogen temperature (Shabatina et al., 2000, 2001, 2005). The film samples have been studied by IR and UVA IS spectroscopy in the temperature range from 80 to 300 K. Two types of complexes were detected, one complex with a metal to ligand... 

Detailed ENDOR measurements have been made by Chan and Hutchison (1972) on LaClj doped with samarium, oihanced in the two odd-neutron isotopes 147,149 (both 1 = j). The energies of the two low-lying doublet levels of J = f, split by the crystal field, as well as the splitting of the J = 1 manifold, have been determined by optical spectroscopy (Varsanyi and Dieke 1961, Magno and Dieke 1962). Also, the size of the 7-mixing (Axe and Dieke 1962) was evaluated from these measurements. The ENDOR experiments determine the net hyperfine interactions in the lowest doublet, together with the effective nuclear Zeeman interaction, the tensor... 

By some reports gadolinium was the first element named for a person, but it was probably really named for the mineral that contained gadolinia, and the mineral was named for Johan Gadolin. By the same token samarium was named for the mineral samarskite, which had been named in honor of a Russian mine official. Colonel Samarski. It is difficult therefore to assert that the name gadolinium was meant to immortalize the chemist any more than the name samarium was meant to immortalize military personnel. What was unique about samarium however was its discovery using a new analytical technique spectroscopy. 

In his opinion, a new previously unknown element contained in didymium was responsible for the appearance of the new lines in the spectrum. He named it decipium from the Latin to deceive, to stupefy and the name proved to be ironical decipium turned out to be a mixture of several REEs both known and unknown ones. Decipium was debunked in 1879 by L. de Boisbaudran of France who played a prominent role in the discovery of new REEs. In the next chapter we shall tell you how he discovered gallium predicted by Mendeleev. Boisbaudran extracted didymium from samarskite and thoroughly studied the sample by spectroscopy. Boisbaudran was a much more skillful experimenter than Delafontaine and he succeeded in separating the impurity from didymium . He named the new element samarium after samarskite, being unaware that samarium was also a mixture of elements. Boisbaudran s discovery was immediately confirmed by Marignac who, after multiple recrystallizations of samarium , separated two fractions which he marked Y and Yp (not to be confused with the symbol of yttrium Y ). The spectrum of the second fraction was identical to the spectrum of samarium . As to the first fraction, we shall have a look at it a little later. 

The steps and missteps in the process of discovering new elements led to caution in accepting a previously unidentified spectroscopic feature as evidence for a new element (Boyd 1959). Chemical characterization was required. For example, masurium was proposed for element 43, and illium and fiorentium were proposed for element 61 based on atomic spectroscopy of extracts from minerals. In retrospect, it is clear that there was evidence for unusual conditions for these elements. For example, above 7N the only mass numbers of stable isotopes of elements with odd atomic number are also odd, and there is only one stable isobar for each odd A. Molybdenum (Mo) has stable isotopes 92, 94—98, and 100. Ruthenium has 96, 98-102, and 104. Niobium has 93, and rhodium 103. Nothing is left for technetium, which would have the best chance for stability at mass numbers 97 and 99. Similarly, either neodymium or samarium has a 3-stable isotope fi om 142 to 150 nothing is left for promethium. 

Yttrium organometallics, NRM spectroscopy Lutetium organometallics, NMR spectroscopy Lanthanum organometallics, NMR spectroscopy Samarium organometallics, NMR spectroscopy Uranium organometallics, NMR spectroscopy Diastereotopic systems, NMR spectroscopy Carbon-13 NMR spectroscopy, paramagnetic complexes Agostic interactions, NMR spectroscopy... 

In 1878 Delafontaine made an important observation. He isolated didymium both from cerite and from the mineral samarskite . Absorption spectra obtained during examination of the two didymium samples were different. To Delafontaine this was an indication that didymium was not a homogenous element This interested Bois-baudran in France. Unlike Delafontaine he used emission and not absorption spectroscopy. He found Hnes showing the presence of a previously unknown element In 1879 he announced the discovery with the information that its name was samarium after the mineral. 

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