Neodymium triflate

Ligand 131 contains both cryptate and crown ether binding units. It reacts with neodymium triflate to give a 1 1 cryptate [Nd c 131]3+ exhibiting NIR luminescence upon excitation at 355 nm. The lifetime of the Nd(4F3/2) level is 347 and 711 ns in methanol and methanol-, respectively, which translates to MeOH 0 using eq. (10b). When barium ions are added to a solution of this complex in acetonitrile, the intensity of the 1.06 pm emission band is reduced substantially, while the lifetime of the Nd(4F3/2) level remains unchanged at about 470 ns. The Ndm ion is therefore not displaced from the cryptand cavity, while its luminescence is modulated by the presence of the Ba2+ ions bound by the crown ether (Coldwell et al., 2006). 

The use of Ln(OTf)3 in the activation of aldehydes other than formaldehyde was also investigated [18]. The model reaction of 1-trimethylsiloxycyclohexene (2) with benzaldehyde under the influence of a catalytic amount of Yb(OTf)3 (10 mol%) was examined. The reaction proceeded smoothly in H20-THF (1 4), but the yields were low when water or THF was used alone. Among several Ln(OTf)3 screened, neodymium triflate (Nd(OTf)3), gadolinium triflate (Gd(OTf)3), Yb(OTf)3, and lutetium triflate (Lu(OTf)3) were quite effective, while the yield of the desired aldol adduct was lower in the presence of lanthanum triflate (La(OTf)3), praseodymium triflate (Pr(OTf)3) or thulium triflate (Tm(OTf)3) (Table 2). 

The permeability of ethanol and higher alcohols through Nafion has not been studied so extensively as methanol permeation. Verma and coworkers reported the permeability coefficients of ethanol through Nafion composites with NdaOa [90], neodymium triflate [91], and erbium triflate [92] and the corresponding Nafion recast membranes. Unexpectedly, the measured P for ethanol differ more than a factor 20 for recast membranes (P between 1.0 10 and 2.8.10 cm. s ). 

Shroti N, Barbora L, Verma A (2011) Neodymium triflate modified Nafion composite membrane for reduced alcohol permeability in direct alcohol fuel cell. Int J Hydrogen Energ 36 14907-14913... 

Catalysis of the aminolysis of epoxides by lanthanide triflates (ytterbium, neodymium and gadolinium trifluoromethanesulphonate) has been reported (e.g. equation 26)68. 

Lanthanide (III) triflates (Ln(OTf)3) react with three equivalents of the l,3-bis(trimethylsilyl)allyl anion to produce neutral, solvated tris(allyl) species [l,3-(SiMe3)2C3H3]3Ln(thf) (Ln = Ce, Nd, Tb). The neodymium complex has three rf -coordinated allyl ligands, with an approximate threefold axis through the Nd-0 bond (11) Nd-C distances range from 2.64 to 2.78 A. 

A solid superacid (stronger than H2SO4 100 %) such as Ti02-S04 as nanosized particles has been successfully used as a filler yielding membranes with conductivities up to 50 % higher than the recast Nafion membrane [88]. Neodymium oxide [90] and triflate [91], along erbium triflate [92] enhance the conductivity of Nafion between 30 % and 40 % when added in concentrations between 3 and 8 wt%. 

Wang reported three-component coupling reaction of aldehydes, amines, and dienes by lanthanide triflate catalyzed aza-Diels-Alder reaction in water [35, 36]. Among lanthanide triflates screened, lanthanum, praseodymium, neodymium, and ytterbium triflate were found to be effective (Table 13.16). It is worth noting that aqueous formaldehyde could be employed as substrate. These reaction conditions were applied in the synthesis of aza-sugars. 

Noteworthy is the neodymium(iii)-triflate-catalyzed reaction of cyclohexadiene with formalin and L-phenylalanine methyl ester, which provides a 3/1 ratio of diastereomers 28 and 29 in an 84% yield. The uncatalyzed reaction results in only a 27% yield of 28 and 29 ... 

Among the seven lanthanides screened, praseodymium(iii), ytterbium(iii) and neodymium(//7) triflates were shown to be most effective. Magnesium chloride and lithium chloride showed no substantial influence on these reactions, thereby ruling out the salt effect for explaining the rate and yield enhancements of lanthanides. The details of the catalytic mechanism of this intriguing lanthanide-mediated effect are under investigation. 

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