Lanthanide complexes amines

The DELFIA assay, the first effective lanthanide-based immunoassay, was developed and commercialized by the early 1980s.108-112 DELFIA (Dissociation Enhanced Lanthanide Fluoro-ImmunoAssay) is a heterogeneous assay which uses a lanthanide complex based on aminocarboxylate ligands such as EDTA, EGTA, or DTPA, linked to the antibody by reaction of appended isothiocyanate groups (e.g., complex (45)) with nucleophilic residues, particularly amines, on the protein surface (Figure 11). 

Complexes of the lanthanides with amine oxides, nitroso compounds, and nitroxide radicals fall under this category. However, only the complexes with the amine oxides have received wide attention. Four comprehensive reviews have appeared on the complexes of amine oxides with various metal ions 142-145). Only a few complexes of the lanthanides have been quoted in these reviews. 

Yang, X.-P. Su, C.-Y. Kang, .-S. Feng, X.-L. Xiao, W.-L. Liu, H.-Q. Studies on lanthanide complexes of the tripodal ligand bis(2-benzimidazolylmethyl)(2-pyridyl-methyl)amine. Crystal structures and luminescence properties. J. Chem. Soc., Dalton Trans. 2000, (19), 3253-3260. 

Matthews, K. D. Kahwa, I. A. Williams, D. J. Preparation, structure, and luminescence of dinuclear lanthanide complexes of a novel imine-amine phenolate macrocycle. Inorg. Chem. 1994, 33,1382-1387. 

Separation of contact and pseudo-contact contributions in paramagnetic lanthanide complexes 372 (L4 = tris 2-[A -methylcarbamoyl-(6-W,A -diethylcarbamoyl)pyridi-ne-2)ethyl]amine ) 390... 

Recently, many aromatic ligands derived from amines have been synthesized and the luminescence properties of their lanthanide complexes have been investigated. The ligand which is composed of an aromatic amine as a chromophore and tetra(acetic acid) as a chelation... 

Insofar as asymmetric synthesis is concerned, some pioneering work was conducted by Marks and co-workers through their demonstration of enantioselectivity in the samarium or lanthanide complex-catalyzed cyclization of aminoalkenes, an analogy of the simple reaction exemplified in Scheme 36. As before, the reaction works best for Se-unsaturated amines where the product of an exocyclic ring closure pathway is a cyclopentylamine. In the most favorable cases, high turnover to the desired product is observed [110] (Scheme 37). 

Lanthanide complexes of amines are prepared in an anhydrous medium to avoid precipitation of lanthanide hydroxides. In one of the procedures, a solution of ethylenediamine in acetonitrile is mixed with a solution of anhydrous lanthanide nitrate or perchlorate [13, 62,63]. 

The impetus for the development of synthesis and characterization of complexes of lanthanides with organic nitrogen donor ligands is due to the search for more efficient luminescent rare earth compounds. One of the difficulties is the risk of precipitating lanthanide hydroxides in the process of synthesis of lanthanide complexes with organic amines. In the early stages, lanthanide complexes of heterocyclic bases of low basicities were prepared in aqueous alcoholic media [224], In the synthesis section it was appropriately pointed out the need for the anhydrous conditions and involved procedures for the preparation of lanthanide complexes of ligands of non-ionizable nature. Some representative complexes of both aliphatic and aromatic amines are listed in Table 4.19. 

The reaction is catalyzed by lanthanide complexes CpjfLnR,41 although noble metal catalysts, notably rhodium, are most widely applied, particularly in asymmetric hydroboration,42 The mechanism is likely to be similar to hydrosilylation. The products may be oxidized with H202 and converted to alcohols or amines. 

It was subsequently found that amine polycarboxylates such as EDTA" gave stronger complexes and much better separations. In practice, some Cu + ions ( retainer ) are added to prevent precipitation of either the free acid H4EDTA or the lanthanide complex... 

Although pyridine and other amine-type ligands form adducts with lanthanide diketonates, few other lanthanide complexes have been made. However, the first homoleptic lanthanide ammine complexes, [Yb(NH3)g] [Cu(S4)2] NH3, [Yb(NH3)s] [Ag(S4)2]-2NH3,and[La(NH3)9] [ 0(84)2],have been synthesised by reactions in aqueous ammonia. ... 

A different mechanism again is involved in the hydroamination reaction catalyzed by lanthanide complexes, Cpff.nR which is applied to the cyclization of unsaturated amines. The mechanism involves the formation of a metal amide species from both the catalysts (by different routes), followed by the turnover —limiting intramolecular insertion of the alkene to give a cr-complex, from which the decomplexed cyclic amine is obtained after reaction with a second molecule of the unsaturated amine19,20,107. 

It is noted that the magnitude of the contact contribution varies considerably between the and resonances. In order to obtain structural information on the lanthanide complexes at least six Gj values are, in general, required (three polar coordinates to fix the position of the lanthanide ion relative to the molecule, two additional angles to define the main magnetic axis orientation, and one signed value for the proportionality constant). The six nuclei used to provide these Gj values need not necessarily be protons. In a later paper Reilley et al. (388) discuss certain refinements of their method and apply it to a wide variety of LSR complexes including those of water, pyridines, alcohols, anilines, aliphatic amines, and ketones. The contact contributions of the C shifts of Ln(DPA)3 and Ln(MDPA)3 complexes are found to be important even for carbons five bonds removed from the lanthanide ion. (390)... 

NOESY NMR spectra were used to characterise the lanthanide complexes Ln(L)3+, where L = tris[(2-pyridyl)methyl]amine or tris[6- (2-7V,7V-diet-hylcarbamoyl)pyridyl methyl]ketone, Ln = La Lu except Pm.1236 The H NMR spectra of Ln(L)Cl3, where L = N403 tripodal ligands, Ln = La - Lu, except Pm, show effective C3v symmetry in solution.1237 H and 13C NMR assignments, based on COSY, NOESY and HMQC data, have beeen made for [LnL]Cl3. H20, where Ln = La, Ce, Eu L = chiral macrocycle derived from (1 R,2R)-1,2-diphenylethylenediamine and 2,6-diformylpyridine.1238... 

Anionic bridged bis(amidinate) lithium lanthanide complexes have been found to be efficient catalysts for the amidahon of aldehydes with amines under mild conditions (Scheme 56). The achvity was found to follow the order of yttrium < neodymium < europium ytterbium. The catalysts are available for the formahon of benzamides derived from pyrrolidine, piperidine, and morpholine with good to excellent yields. In comparison with the corresponding neutral complexes, the anionic complexes showed higher achvity and a wider range of scope for the amines. A cooperation of the lanthanide and lithium metals in this process was proposed to contribute to the high activity of these catalysts [66,67]. 

Selective alkylation. The reactivities of amines toward alkylating agents can be clearly differentiated in the presence of a lanthanide complex. Thus a tertiary amine undergo methylation (Mel or Me SOi), while a primary amino group remains unchanged. 

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