Complexes of yttrium

A scandium complex, Cp ScH, also polymerizes ethylene, but does not polymerize propylene and isobutene [125]. On the other hand, a linked amidocyclo-pentadienyl complex [ Me2Si( / 5-C5 Me4)( /1 -NCMe3) Sc(H)(PMe3)] 2 slowly polymerizes propylene, 1-butene, and 1-pentene to yield atactic polymers with low molecular weight (Mn = 3000-7000) [126, 115]. A chiral, C2-symmetric ansa-metallocene complex of yttrium, [rac-Me2Si(C5H2SiMe3-2-Buf-4)2YH]2, polymerizes propylene, 1-butene, 1-pentene, and 1-hexene slowly over a period of several days at 25°C to afford isotactic polymers with modest molecular weight [114]. 

Marks et al. reported the co-polymerization of ethylene and 1-hexene by using ansa-type complexes of lanthanide metals [127]. Recently, bulky alkyl substituted ansa-type metallocene complexes of yttrium have been reported to exhibit high activity for the polymerization of 1-hexane. [114, 119, 128]... 

The measurement of stability constants of complexes of yttrium, lanthanide, and actinide ions with oxalate, citrate, edta, and 1,2-diaminocyclohexanetetra-acetate ligands has revealed that there is a slight increase in the stability of complexes of the /-electron elements, relative to the others. A series of citric acid (H cit) complexes of the lanthanides have been investigated by ion-exchange methods and the species [Ln(H2cit)]", [Ln(H2cit)2] , [Ln-(Hcit)], and [Ln(Hcit))2] were detected. Simple and mixed complexes of dl- and jeso-tartaric acid have been obtained with La " and Nd ions, and the stability constants of lactate, pyruvate, and x-alaninate complexes of Eu and Am " in water have been determined. 

The hydrides 44b have been found to polymerize ethylene and react with a variety of protic reagents such as terminal alkynes and nitriles. Catalytic effects in the hydroboration of olefins have also been observed [27]. A well-defined /i-ethynyl complex of yttrium is formed by protolysis of the alkyl derivative 38b with acetylene (Eq. 18). Figure 14 shows the dimeric structure of 45b with bridging ethynyl ligands [27, 65]. 

Fig. 1 m-Terphenyl complexes of yttrium stabilised by the 2,6-Nap2C6H3 and 2,6-Anis2C6H3 ligands... 

In this way, the indenyl tethered NHC complexes of yttrium, lutetiiim and scandium were synthesised [135] each still bearing two potentially reactive trimethylsilylmethyl substituents. The potential as single component or cationic (after activation with MAO) catalysts for the polymerisation of olefins was pointed out by the authors, but no studies have as yet been reported. The same can of course be said about the corresponding early transition metal complexes of titanium, zirconium, vanadium and chromium [134,136] where the synthesis of the proligands and the transition metal complexes were reported, but no catalytic studies performed. 

The coordination chemistry of the aminotroponiminates has been reviewed.139 A homoleptic aminotroponiminate complex of yttrium has been prepared and studied by X-ray crystallography and density functional theory calculations.140... 

CCC (1987) contains a section on sulfoxides, amide, amine oxides, and related ligands that have sections on phosphine oxides and arsine oxides.159 Phosphine and arsine oxide complexes of yttrium and the lanthanides were highlighted in CCC (1987).1 Scandium and yttrium phosphine oxide complexes have been reinvestigated and characterized by multinuclear NMR and X-ray... 

Liu X and Byrne R (1995) Comparative carbonate complexation of yttrium and gadolinium at 25°C and 0.7 mol dm ionic strength. Marine Chem 51 213-221. 

Porphyrin complexes of yttrium, lanthanum, cerium, praesodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and thorium can be synthesized using this method. 

Figure 10 Cyclopentadienyl-amide hydride complex of yttrium...

In view of the known complexes, the presence of f-electrons might appear as a factor of destabilisation for ytterbium and late lanthanides derivatives. An exhaustive comparative study of analogous complexes of yttrium and late lanthanides appears necessary to establish a sound comparison of the stability and reactivity between these complexes. This would allow us to bring new light on the role played by the/electrons. 

Table 2 Hydrazine complexes of yttrium, lanthanum, and some lanthanides...

Ligand exchange reactions of triphenylphosphine oxide complexes of yttrium compounds were studied. ... 

Vallarino LM, Leif RC (1997) Macrocycle complexes of yttrium, the lanthanides and the actinides having peripheral coupling functionalities continuation-in-part. US Patent 5,696,240... 

TABLE 1. Proton NMR spectra of some selected bis(cyclopentadienyl) complexes of yttrium and scandium (Cp = C5H5 Cp = CH3C5H1+)... 

Figure 12.7 TG and DTG curves of complex of yttrium bromide with glycine [2j.

Complexes of Yttrium and the Lanthanides with Simple Ligands... 

The red-violet complex of boric acid and catechol violet reacts selectively with yttrium salts to form a blue complex of yttrium and catechol violet. 

The study of catalytic processes involving rare earths has been advanced by the synthesis and characterization of alkyl and hydride complexes of yttrium (Evans et al., 1984b), which in part were investigated because they provided NMR information via Y-H and Y-C coupling. Although yttrium is not considered a lanthanide, that row of elements exhibits reactivities similar to yttrium, and subsequent comparisons are reasonably valid. 

Formimidoyl complexes of yttrium are formed in the interaction of tertbutylisocianate with yttrium hydride [188] ... 

K. C. Hultzsch, T. P. Spaniol, J. Okuda, Half-sandwich alkyl and hydrido complexes of yttrium convenient synthesis and polymerization catalysis of polar monomers. Angew. Chem. Int. Ed. 38, 1999 227. 

Beloedova TV, Kazakova LV, SkorikNA(1972) Stability of rare earth and yttrium citrate complexes in water and water-alcohol mixtures. Zhum Neorg Khim 17 1580-1583 Tripathy KK, Patnaik RK (1973) Citrate complex of yttrium(III). Acta Chim Acad Sci Hung 79 279-288... 

Sal nikov, Yu I, Devyatov FV (1983) Mixed-center citrate complexes of yttrium group lanthanide and gadolinium(III) ions. Zhurn Neorg Khim 28 606-610... 

Stepanov AV (1971) Comparative stability of complexes of yttrium, and some rare-earth and actinide elements with anions of oxalic, citric, ethylenediaminetetraacetic and 1,2-cy-clohexanediaminetetraacetic acids. ZhumNeorg Khim 16 2981 2985 Ohyoshi E, Ohyoshi A (1971) Complexes with polybasic acid americium(III) citrate complexes. J Inorg Nucl Chem 33 4265-4273... 

Following some detailed studies of kinetically inert complexes of yttrium - for targeted radiotherapy - and of gadolinium, for use as contrast agents in magnetic resonance imaging, we were attracted by the chemical versatility of single component, luminescent lanthanide complexes. The monoanionic tetracarboxylate and... 

Pinkerton A A, Meseri Y, Rieder C (1978) Preparation and characterization of dithiophosphinato-complexes of yttrium and the lanthanoids. J Chem Soc Dalton Trans 85-90... 

Scheme 5 Unusual hydrogen migration/C—H bond activation cascade reactivity of orfho-metalated 2-phenylpyridine complexes of yttrium and lutetium.

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