2 research outputs found
Synthesis of <i>N</i>âAryloxy-β-diketiminate Ligands and Coordination to Zirconium, Ytterbium, Thorium, and Uranium
Two examples of <i>N</i>-aryloxy-β-diketiminate
dianions (<b>11a</b>,<b>b</b>) have been synthesized on
a multigram scale, in four steps, from commercially available chemicals.
The synthetic scheme relies on the sequential addition of 2,6-diisopropylaniline
and 2-amino-4-<i>tert</i>-butylphenol (<b>1a</b>)
(or 2-amino-4,6-di-<i>tert</i>-butylphenol (<b>1b</b>)) to acetylacetone, using Et<sub>3</sub>OBF<sub>4</sub> as an activation
reagent. Both the nature of the activation reagent and the order of
addition of the primary amines have a major impact on the outcome
of the reaction, and acid catalysts (such as sulfuric acid or <i>p</i>-toluenesulfonic acid) lead to decomposition of the β-diketiminate
backbone via formation of a benzoxazole derivative (<b>3a</b>,<b>b</b>). Using dianions <b>11a</b>,<b>b</b>,
mono- and bisÂ(<i>N</i>-aryloxy-β-diketiminate) complexes
of zirconiumÂ(IV), ytterbiumÂ(III), thoriumÂ(IV), and uraniumÂ(IV) have
been synthesized (<b>12</b>â<b>18</b>), by salt
metathesis reactions, and characterized by a combination of <sup>1</sup>H/<sup>13</sup>C NMR spectroscopy, elemental analysis, and X-ray
crystallography. The two ligands differ in their steric bulk and exhibit
different coordination behaviors, which were rationalized on the basis
of geometric considerations
Bimetallic Cleavage of Aromatic CâH Bonds by Rare-Earth-Metal Complexes
A new
type of CâH bond activation mediated by rare-earth metals under
reducing conditions is reported. The synergy between reductants and
rare-earth-metal complexes allows the cleavage of unactivated aromatic
CâH bonds. The reaction between rare-earth-metal iodides supported
by a 1,1â˛-ferrocenediamide ligand and potassium graphite in
benzene leads to the formation of a 1:1 metal molar ratio of the corresponding
metal hydride and metal phenyl complex. A proposed mechanism involving an inverse sandwich arene bimetallic intermediate is supported
by experimental and computational studies