Neodymium , complexing with

Scheme 44 Isolation of an alkylated neodymium complex with three different ligands from the reaction of neodymium diisopropylamide with TMA [207]...

Neodymium complexes with bulky an5a-bis(cyclopentadienyl) hgands used in combination with magnesinm dialkyls were shown to he able to ohgomerize 1-octene with the occurence of chain transfer reactions Bogaert, S. Chenal, T. Mortrenx, A. Nowogrocki, G. Lehmann, C. W. Carpentier, J.-F. Organometallics 2001, 20, 199. 

Diorganotin(IV) complexes with 4//-pyrido[l,2-n]pyrimidin-4-ones 109 (96MI4), complexes of 2-methyl- and 2-methyl-8-nitro-9-hydroxy-4//-pyrido[l,2-n]pyrimidin-4-ones with Ag(I), Cu(II), Ni(II), Co(II), and Mn(II) ions (00MI23), 2,4-dimethyl-9-hydroxypyrido[l, 2-n]pyrimidinium perchlorate and its complexes with prasedynium, neodymium, samarium and europium (00MI24) were characterized by UV spectroscopy. 

Although efficient for the intramolecular hydroamination/cyclization (abbreviated IH below) of aminoalkenes (see below), organolanthanides exhibit a much lower catalytic activity for the intermolecular hydroamination of aUcenes, as exemplified by the reaction of n-PrNH2 with 1-pentene catalyzed by a neodymium complex (Eq. 4.17) [127]. 

X 109 and 8. 9 x 109 s 1 for Ndm and Ybm, respectively. Both the above-described in-termolecular mechanism, as well as an intramolecular pathway in the ternary complex with aad which forms in solution, are responsible for the observation of NIR luminescence in these systems. Addition of water to the toluene solutions quenches the NIR luminescence, while it enhances the visible CL emission of the corresponding solution of Eum and Tbm (Voloshin et al., 2000c). Neodymium and ytterbium tris(benzoyltrifluoroacetonates) display the same CL as tta complexes, although for Ybm its intensity is about 2.5 times lower than for the tta chelate. On the other hand, almost no CL is detected for acetylacetonate complexes (Voloshin et al., 2000a). Thermal or photochemical decomposition of aad also triggers CL from [Pr(dpm)3] and Pr(fod)3], both in the visible (from the 3Pi, 3Po, and 1D2 levels) and in the NIR at 850 nm ( Do -> 3F2 transition) and 1100 nm ( D2 3F4 transition). The excited... 

Scheme 10 Neodymium complex [Me2Si(3-Me3SiC5H3)2]NdCl used for copolymerization of BD and ethylene [306], reprinted with permission of Wiley-VCH Verlag GmbH Co. KGaA...

In 2004 Carpentier and co-workers were the first who isolated and characterized the active species from a Nd alcoholate/MgR2 mixture. The reaction of either a trinuclear or a monomeric Nd alcoholate precursor with Mg(CH2SiMe3)2 (Et20) yields an alkyl neodymium complex and a new het-erobimetallic Nd-Mg complex. The latter complex is considered to be the active species for the investigated catalyst system [621],... 

The ratio of the size of the metal ion and the radius of the internal cavity of the macrocyclic polyether determines the stoichiometry of these complexes. The stoichiometry of these complexes also depends on the coordinating ability of the anion associated with the lanthanide. For example, 12-crown-4 ether forms a bis complex with lanthanide perchlorate in acetonitrile while a 1 1 complex is formed when lanthanide nitrate is used in the synthesis [66]. Unusual stoichiometries of M L are observed when L = 12 crown-4 ether and M is lanthanide trifluoroacetate [67]. In the case of 18-crown-6 ligand and neodymium nitrate a 4 3 stoichiometry has been observed for M L. The composition of the complex [68] has been found to be two units of [Nd(18-crown-6)(N03)]2+ and [Nd(NCh)<--)]3. A similar situation is encountered [69] when L = 2.2.2 cryptand and one has [Eu(N03)5-H20]2- anions and [Eu(2.2.2)N03]+ cations. It is important to note that traces of moisture can lead to polynuclear macrocyclic complexes containing hydroxy lanthanide ions. Thus it is imperative that the synthesis of macrocyclic complexes be performed under anhydrous conditions. 

The malonate complex of Eu(III), Eu2(malonate)3 8H2O is interesting since there are two different coordination geometries, and only five of the water molecules are coordinated [167], One of the Eu ions is eight-coordinate in the form of a distorted square antiprism and the other Eu ion is nine-coordinate, distorted tricapped trigonal prism. In the analogous neodymium complex, six water molecules are coordinated because of the difference in ionic radius. The neodymium complex is nine-coordinate with monocapped antiprismatic geometry [168]. 

The only complexes of lanthanum or cerium to be described are [La(terpy)3][C104]3 175) and Ce(terpy)Cl3 H20 411). The lanthanum compound is a 1 3 electrolyte in MeCN or MeN02, and is almost certainly a nine-coordinate mononuclear species the structure of the cerium compound is not known with any certainty. A number of workers have reported hydrated 1 1 complexes of terpy with praseodymium chloride 376,411,438), and the complex PrCl3(terpy)-8H20 has been structurally characterized 376). The metal is in nine-coordinate monocapped square-antiprismatic [Pr(terpy)Cl(H20)5] cations (Fig. 24). Complexes with a 1 1 stoichiometry have also been described for neodymium 33, 409, 411, 413, 417), samarium 33, 411, 412), europium 33, 316, 411, 414, 417), gadolinium 33, 411), terbium 316, 410, 414), dysprosium 33, 410, 412), holmium 33, 410), erbium 33, 410, 417), thulium 410, 412), and ytterbium 410). The 1 2 stoichiometry has only been observed with the later lanthanides, europium 33, 411, 414), gadolinium, dysprosium, and erbium 33). 

The nitrate ion activities in the aqueous phase were measured with a nitrate ion selective electrode taking into account the presence of high hydrogen ion concentration by calibration of the nitrate electrode with nitric acid. The nitrate ion concentration in the organic phase owing to the extraction of neodymium complexes by HDEHP was determined by back-extraction of the organic phase with 3M sulfuric acid, dilution, and analysis with a nitrate ion electrode calibrated for different nitrate and sulfate concentrations. The amount of the nitrate species extracted into the organic phase increases as the initial neodymium nitrate concentration increases. 

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