Lanthanum macrocyclic complexes

Fenton, D. E. Kitchen, S. J. Spencer, . M. Tamburini, S. Vigato, P. A. Complexes of ligands providing endogenous bridges. Part 5. Solution studies on a novel 3 + 3 hexamine Schiff-base macrocyclic complex of lanthanum. J. Chem. Soc., Dalton Trans. 1988, 685-690. 

A number of other complexes involve the lanthanide bonding to nitrogens in rings, either in aza crowns or in more classic macrocycles like cyclen. 1,4,7,10,13-pentaazacyclopentadecane (L) forms nitrate complexes [Ln(L)(N03)3] (Ln = Y, La Yb except Ce, Pm, Ho) the structure of [La(L)(N03)3] shows it to have 11-coordinate lanthanum As another example of structurally characterised... 

The parent oxacalix[3] arenas show little ability to bind alkali metals,however, a range of quaternary ammonium cations are attracted to the symmetric cavity. Deprotonation of the phenol moieties allows them to bind to transition metals (scandium, titanium, vanadium, rhodium, molybdenum, gold, etc.), lanthanides (lutetium. yttrium, and lanthanum), and actinides (uranium as uranyl). Oxacalix[3]arenes derivatized on the lower rim can complex gallium, mercury, and alkali metals, including sodium, in a manner reminiscent of natural transmembrane cation filters. One major use was to purify crude samples of fullerenes. The pseudo-Cs symmetry of the macrocyclic cavity is complementary to threefold symmetry elements of Cgo. which binds preferentially in... 

The Schiff-base macrocycle H2L1733 (Eq. 8.39) with increased coordination capacity has been assembled in the presence of lanthanum(III) acetate from 6,6 -bis(aminomethyl)-2,2 -bipyridyl and 2,6-diformyl-4-methylphenol and isolated as the homodinuclear complex [La2(L1733)(02CCH3)4]4CH3CN-3H20 [103]. X-Ray crystallographic study of the latter showed that all ten donor atoms of the macrocycle are involved in coordination to two identical La centres. A coordination number of 10 for each La is completed by two bidentate acetate anions. Reduc-... 

A non-template synthesis of the 1 + 1 macrocycle H2LI77O derived from condensation of the (2-hydroxybenzaldehyde-3-yl)-0-(CH2CH20)3-(3-yl-2-hydroxy-benzaldehyde) and 1,2-diaminoethane in acetonitrile has been reported and its structure confirmed by X-ray diffraction [125], Direct complexation with LaCls-7H2O in methanol yields [La(H2L1770)(H2O)4]Cl3. Single crystal X-ray analysis revealed that lanthanum is 10-coordinated, like barium in the complexes shown in Figures 8-7, 8-8 and 8-10. It should be mentioned that lanthanide(III) ions have not been employed so far as templates for the construction of related macrocycles, in which a softer donor site is combined with a hard polyether binding site. 

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