Lanthanate complexes

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... 

Wostyn et al. [61] have reported the molecular nonlinear optical polarizability of lanthanate complexes containing stilbazolium ions. Their experimental results indicate that the hyperpolarizability is independent of the nature of the lanthanide, though the complex anion size is a function of the size of the ligand on the lanthanide cation. Andreu et al. [55] have synthesized a new chiral cyanine dye, 4 -[2-(methoxymethyl)pyrrolidinyl]-l-methylstilbazolium iodide (MPMS + I). They have reported that MPMS +1 exhibits phase-matched SHG with the efficiency of up to 80 times that of urea. 

Marinic, M., Piantanida, I., Rusak, G., Zinic, M. (2006). Interactions of quercetin and its lanthane complex with double stranded DNA/RNA and single stranded RNA spectrophotometric sensing of poly G. Journal of Inorganic Biochemistry, 100, 288-298. 

Wang et al. (1995b) reported thermotropic mesomorphism for tetrakis l-phettyl-3-methyl-4-berrzoyl-5-pyrazolanato lanthanate complexes with amphiphilic hemicyanines as counter ions. However, further study revealed that these corrrplexes are not liqirid-crystalline... 

Scheme47 DIBAH-mediated [amide] -[hydride] transformation in nnsa-lanthan-idocene(III) complexes (Ln = Y, Ho) [213]...

It was one of Berzelius assistants and the curator of the mineral collections of the Stockholm Academy of Sciences, Carl Gustaf Mosander (1797-1858), who demonstrated the complexity of both "yttria" and "ceria." When Mosander heated some "cerium" nitrate in 1839, the salt partly decomposed, and on a treatment with dilute nitric acid, he succeeded in extracting a new earth. He called the new element lanthanum (German Lanthan) and its oxide "lanthana." Mosander retained the old name ceria (Ce) for the insoluble portion of the "ceric" oxide in nitric acid. 

Figure 1.25 The anion structure in the complex KsRE2(C204)7-14H20 [23]. (Reprinted from/nor an-ica ChimicaActa, 82, no. 2, LA. Kahwa, RR. Fronczek, and J. Selbin, The crystal and molecular structures of potassium-ti-oxalato-di [tris-oxalato-lanthanate(III)]-14-hydrates K8[0x3Ln0xLn0x3]14H20 [Ln = Tb, Dy, Er, Yb, Y], 167-172, 1984, with permission from Elsevier.)...

Lanthanide ions continue to be very widely used as shift reagents for substrate molecules (Section III.F). There is, however, considerable interest in the NMR properties of the lanthanide complexes themselves. The isotropic shifts of the latter are invariably dominated by dipolar interactions between the lanthanide ion and the nucleus under question. Bleaney (156) has predicted that the dipolar shift will be dominated by a component which varies as T around room temperature whereas Horrocks et a/. (157,158) predict a more complex temperature dependence. Hill et al. (159) have examined the temperature dependence of some tetraethylammonium tetrakis-N,N-diethyldithiocarbamato-lanthanate(iii) salts, Et4N Ln(dtc)4, in an attempt to clarify the situation. The observed temperature dependences are complex and both contact and dipolar contributions had to be considered in the form ... 

Further procedures are based on a discoloration of organic dyes with zir-conium(IV) salts (zirconium-eriochromcyanine R), leading to the formation of a blue fluoride complex with trivalent lanthane and alizarine complexone, or they depend on the measurement with a fluoride ion selective electrode based on lanthanum fluoride [18]. 

The two classes of complexes containing a bis(f8]annulene)-lanthanate(III) anion are those that contain an alkali cation and those that contain the complex [8]annulenelanthanatedII) cation. One of the classes, the alkali salts of the bis([8lannulene)lanthanate(III) anions, have been prepared by a variety of methods. The first of the methods, and the one which is of the roost synthetic utility, is the direct reaction of the di-alkali salt of (8]annulene dianion with the anhydrous lanthanide trichloride. The synthesis can be accomplished either by the addition of a suspension of the lanthanide salt in THF to a THF solution of the dianion.or by the reverse method, the addition of a solution of dianion to a suspension of the lanthanide (III) salt. 0... 

The latter method is preferable, since in this manner of addition of the reagents the lanthanide trichloride is never exposed to an excess of reducing [8]annulene dianion. Bis([8]annulene)lanthanate(III) and -yttriate(III) anions have also been reported. 7 similiarly. the bis([81annulene)lanthanate(III) anion complexes from... 

It is postulated from these equilibria that in the reaction of [8]annulene dianion with a lanthanide(III) chloride the [8)annulene-lanthanate(III) chloride is formed initially as a isolable intermediate of the reaction. The mono-ring intermediate then reacts with additional [8]annulene dianion to form the bis[8]annulene complexes. 

The bis([8]annulene)lanthanate(III) anions which are complexed by an [8]annulenelanthanate(III) cation are the only other class of complexes which contain two [8]annulene dianions in a sandwich arrangement about a lanthanide(III) ion. This class was first reported for the cerium(III) ion, from the reduction of a cerium(IV) alkoxide with triethylaluminum in the presence of cyclooctatetraene.3 ... 

In the neodymium complex, the presence of a second lanthanide(III) only distorts the bis([0]annulene)lanthanate(III) ion. The thermodynamic driving force for neodymium to form a covalent ir-bond with cyclooc-tatetraene is not sufficient to overcome the coulombic attraction between [8]annulene dianion and a lanthanide(III) ion. 

Monomeric lanthanide alkoxides are generally imstable, unless they are stabilized by bulky substituents (20). Spassky and co-workers have shown that clustered lanthanide alkoxides Ln5(/i-0)(0-i-C3H7)i3 can initiate ROP of DL-lactide in dichloromethane (56). The following order of reactivity (La Sm Yb) has been reported. Low polydispersity is seen even at high conversion and long reaction time, except in case of lanthane because of exceedingly high reactivity and low selectivity. ROP of -CL is more complex, and transesterification reactions can occur before the monomer conversion is complete. 

Lanthanide and Actinide Elements.- The chemistry of organo-lanthan-Ide compounds, including Cp and indenyl complexes, has been re-... 

In most of early papers dedicated to the aforementioned complexes the authors accepted or supposed the existence of a direct Ln-M bond in these compounds. As a confirmation for the supposition they used the infrared spectra of the products in the region of CO stretching frequency as well as the reduction reactions of Sm(III) and Yb(III) metalcarbonyls to Ln(II) derivatives by sodium naphthalenide. However, the X-ray diffraction analysis of l2SmCo(CO)4(THF)5, Cl2LuCo(CO)4(THF)5 and the lanthan-molybdenum complex La[MoCp(CO)3]3(THF)6 has shown that quoted above complexes have an ionic nature and can exist as a separated ionic pair or as a contact ionic pair with the isocarbonyl bridge Ln-OC-M. 

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