Lanthanum complex

Alizarin fluorine blue lanthanum complex preparation I84 ... 

Lanthanum, pentaaquatrinitrato-structure, 1, 99 Lanthanum complexes phthalocyanines, 2,864 porphyrins, 2,822... 

The coordination chemistry of ancillary amidinate ligands with a pyridine functionality has been described. Magnesium, aluminum, zirconium, and lanthanum complexes have been prepared in which the amidinate anions act as tridentate, six-electron-donor ligands Amidinate ligands containing quinolyl substituents were constructed in the coordination sphere of lanthanide... 

Heath JR, O Brien SC, Zhang Q, Liu Y, Curl RF, Tittel FK, Smalley RE (1985) Lanthanum complexes of spheroidal carbon shells. J. Am. Chem. Soc. 107 7779-7780. 

Okabayasi et al. used two identical columns containing Alizarin-Fluorine Blue sulphonate-lanthanum complex in an alternate fashion in order to increase the sample throughput in the preconcentration/separation of fluoride prior to its determination by use of an ISE (Fig. 4.14.B). By switching valve SV, the analyte in a sample was measured and eluted while that in the next sample was retained in the odier column [129]. 

The lanthanum complex (Scheme 9) has the coordination number nine with two NO3 ions bidentately bound in the solid state, while in solution only one nitrate group is coordinated. H2dapsox is symmetrically pentadentately coordinated in the a-oxyazine form (Scheme 9). 

The complex anions [M(edta)(H20)3] where M = Pr, Sm, Gd,410 Tb411 and Dy412 all have similar coordination to the lanthanum complex, but for Er and Yb, [M(edta)(H20)2] , which are eight-coordinated, are obtained.412,413 The change in coordination number occurs at some point in the Ho area. Of course, it is by no means certain that a change, if there is one, occurs at exactly the same position in the series in solution. 

Asymmetric amplification has also been observed in lanthanum-catalyzed nitro-aldol reaction, Shibasaki used a chiral lanthanum complex 15 prepared from LaCl3 and dilithium alkoxide of chiral BINOL for the enantioselective aldol reaction between naphthoxyacetaldehyde 14 and nitromethane (Scheme 9.11) [26]. When chiral catalyst 15 was prepared from BINOL with 56% ee, the corresponding aldol adduct 16 with 68% ee was obtained. This result indicates that the lanthanum 15 complex should exist as oligomer(s). 

The lanthanum complex shown in Eq. (9a) is a rare example of a Schiff base derivative synthesized in nonaqueous solution [131]. 8-Coordination is accomplished by two tripleclinching aryloxide ligands, a phenolic contact of a free... 

NMR studies indicated that dissociation of the encapsulated lanthanum complexes varied dramatically with the ligand. The La(TCEC)3+ complex contains pendent groups that form a six-membered ring. This... 

All the hexaisothiocynato complexes of praseodymium to lutetium and yttrium are isostructural. The formula of the lanthanum complex is (GtH LafNCS) but its structure is not known. Since lanthanum is large it may adopt six-coordination less readily. Another example of six-coordination is hexakis antipyrene yttrium(III) iodide whose structure is shown in Fig. 5.7. The antipyrene ligand is large and the six oxygen atoms coordinated to yttrium form an octahedron with S6 molecular symmetry. 

Intra molecular Yb-7r interaction [2.978(6) A] from one of the phenyl substituents has been observed in the Yb complex [265]. A bridging naphthalene unit is present in the lanthanum complex connecting two Lal2(THF)3 units [266]. 

Thermal decomposition of lanthanide complexes of 4-A7-(4 -antipyrylmethylidene)/ amino antipyrine is found to occur in three stages [88] and the phenomenological data are given in Table 7.28. In the case of the lanthanum complex, the three stages of decomposition are as follows ... 

The eight-coordinate tetrakis(diethyldithiocarbamate) lanthanide complexes are isomor-phous and the lanthanum complex has a quasi-tetrahedral configuration of the four CS2 chelate groups. The transition frequencies and dipole strengths of these complexes available over the accessible f-f manifold allowed the extraction of the Judd-Ofelt intensity parameters Qx for k = 2, 4, 6 by standard least squares methods [112,113]. The values of observed Qx and calculated Q, values are given in Table 8.10. The three components of f2() are... 

Scheme 12. Chiral lanthanum complex as catalyst in the asymmetric nitro-aldol reaction according to Shibasaki.

The lanthanide complexes are soluble in ethers like Et20 or THE. They are catalysts for the enantioselective reduction of aldehydes, with best results for the lanthanum complex. Thus the yield is 72% when M = La, but 50% when M = Yb more strikingly, the enantiomeric excess is 69% for the La complex but only 3% when the Yb complex was... 

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