Organolanthanide-ligand complexes

The organolanthanide(II) complexes with tetrahydro-2H-pyranyl- or N-piperidineethyl-functionalized fluorenyl ligands [r 5 r l-C5[ IyOCI I2C 3I Ix]2 Ln and [ri ri -Qd IKINCI I2CII2C13I L]2Ln (Ln = Eu, Yb) were prepared and used in both CL and LA polymerization experiments.64... 

Organolanthanide(lll) complexes with ri coordinated alkene or aUcyne ligands are very rare. For alkene complexes of Ln(II) compounds, see Section 11. The coordination of the... 

Frequently, the preparation of a distinct mixed-ligand complex, LcMXm (Lc = ligand bonded via M-C bonds), is quite a difficult task, in particular if the starting material involves a pure metal halide. In organolanthanide chemistry, however, an almost unique and very effective route to arrive at a large variety of CpnLnXm systems (Cp = r -CsHs) is offered by eq. (1)... 

A review article entitled "Bulky amido ligands in rare-earth chemistry Syntheses, structures, and catalysis" has been published by Roesky. Benzamidinate ligands are briefly mentioned in this contexD The use of bulky benzamidinate ligands in organolanthanide chemistry was also briefly mentioned in a review article by Okuda et al. devoted to "Cationic alkyl complexes of the rare-earth metals S mthesis, structure, and reactivity." Particularly mentioned in this article are reactions of neutral bis(alkyl) lanthanide benzamidinates with [NMe2HPh][BPh4] which result in the formation of thermally robust ion pairs (Scheme 55). ... 

The metal vapor reaction products differed from traditional organolanthanide complexes in many ways. First, the observed stoichiometries had low ligand to metal ratios. For example, the ytterbium and samarium 3-hexyne products (Reaction 4) had formal ligand to metal ratios of one, whereas most organolanthanides are commonly nine or ten coordinate (6-10). Second, the stoichiometries varied in an... 

The central point in this consideration is the Ln-OH moiety, the preferred formation of which is considered to be a dilemma in organolanthanide chemistry. Organolanthanide compounds containing Ln-X a-bonds such as alkyls, amides and alkoxides readily hydrolyze when exposed to moist air, with the formation of the hydroxides. Lanthanide complexes with Ln-C linkages are considered to be oversensitive compounds [89]. Even ligands with lower pKa values than water, as exemplified by substituted phenol ligands, tend to hydrolyze in organic solvents because the insoluble hydroxides formed act as... 

Considering homoleptic organolanthanide species the reader will get a rough overview of the ligands commonly examined. Figs. 7-10 classify structurally characterized complexes according to their shortest intramolecular Ln-X contact [155], Figs. 7-9 show derivatives of Ln(III) in the upper half and... 

Michael reactions) [176], have been considered as alternative A-type spectator environments. The transfer of the catalytic substance of Schiff-base ligands, established in the work of Jacobsen [177], should further stimulate research in this area since organolanthanide complexes, as depicted in Scheme VII, are now available [178]. 

The efficiency of functionalized cyclopentadienyl complexes is meanwhile well established [78,191-202]. Because cyclopentadienyl ligands still dominate the field of organolanthanide chemistry, a selection of the functionalized ligands utilized is depicted in Fig. 11. In the field of aryl complexes, which represented the first well-characterized homoleptic derivatives [203], multiple functionalization has already been started [204]. 

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