Lanthanide complexes azides

The calculation results are shown in table II. We also report formation constants determined from spectrophotometry for Ho and Nd, and by solvent extraction for Er. Without going into detail for these two methods, it may be noted that the results show fair agreement. That fact points out the inner sphere character of orthophenanthrolinium lanthanous complexes. The main absorption band of Am (III] is modified by the presence of orthophenanthroline. We used these spectral variations to calculate the formation constants of Am (III], as described in the previous paragraph. As for azide complexes, we observed that Am monoorthophe-nanthroline is more stable than the equivalent lanthanide complex, and for the bis orthophenanthroline species, the difference... 

Further elaboration of 4 can be accomplished to install assorted functional groups of relevance for proton-transfer relays (Figure 3.5). For example, hydrolysis provides the dicarboxylic acid-appended terpy 5 [32], reduction with borane and hydrolysis yields the aminomethyl-terpy 6 [33], addition of azide provides the tetrazole-substituted terpy 7 [32], and treatment with hydrazine yields 8 [34]. Compounds 5-7 have been utilized as ligands for studying luminescence in lanthanide complexes [32, 33], but to our knowledge, have not yet been described in the catalysis literature. 

Adjuvants such as fluoride ions, were shown to suppress the quenching effect from uric acid present in serum sample [10]. Additionally, a lanthanide complex designed for ceU-based assay should be insensitive to luminescence quenching by azide [27], which is a common internalization inhibitor used in ligand-receptor binding studies [28]. 

In comparison with the asymmetric epoxide-opening reactions described above in Section 9.4, catalytic desymmetrizations of meso-aziridines have relatively limited precedence [151]. Kanai and Shibasaki have disclosed a number of promising results obtained with lanthanide complexes of the chiral phosphinoxide ligand 193 (Scheme 9.24) [152, 153]. These efforts were showcased in the desymmetrization of meso-aziridine 192 with TMSN j to provide azide 194 in 96% yield and 91 % ee. Adduct 194 was subsequently converted into the anti-influenza drug oseltamivir phosphate (Tamiflu, 195) [153]. 

Association between lanthanide ions and azide or thiocyanate ions has been studied in solution by electronic, Raman and NMR spectroscopy.186,187 The complexation constant in water between Nd3+ and N3 is approximately 2.5. Longitudinal relaxation time studies for Gd-Dy indicate that the M—N—NN angle is bent (135° approximately). 

This paper reports the results of investigations of the complex formation between actinide or lanthanide ions and azide or orthophenanthroline. The aim of this work was first to confirm whether these relatively soft ligands give complexes of different stabilities with the trivalent lanthanide and actinide ions, as a consequence of the broader extension of 5f orbitals as compared with 4f. Secondly, we attempted to use the results in actinide chemical separation processes. 

Azide complexes. The aqueous trivalent actinide and lanthanide azides complexes were examined by two techniques ... 

I. Basic Azides of Yttrium, Some Lanthanides, and Azido Complexes of Uranium... 

The emphasis of work by French researchers has been the use of soft-donor extractants and complexants to enhance actinide/lanthanide group separation (Vitorge 1985, Musikas et al. 1980, Musikas 1985). The relative stability constants for lanthanide and actinide azide complexes reported by Musikas etal. (1980) suggest that hydrazoic acid could function as a useful reagent for this separation. This is confirmed in a later report for Am/Eu separation (Musikas 1985) in which americium extraction is suppressed by complex formation with azide. The separation factors are not very different from those reported by Sekine (1965) using SCN as the complexant in TBP extraction. However, Choppin and Barber (1989) find that, while the trivalent actinide-azide stability constants are somewhat larger than those of the trivalent lanthanides, the complexation enthalpies calculated from the temperature coefficient of the / s do not support the existence of a covalent bonding contribution. 

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