Copper(I) Ethylene Complexes
Supported by 1,3,5-Triazapentadienyl
Ligands with Electron-Withdrawing Groups
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Abstract
The fluorinated 1,3,5-triazapentadienyl ligands [N{(C<sub>3</sub>F<sub>7</sub>)C(2-(NO<sub>2</sub>)C<sub>6</sub>H<sub>4</sub>)N}<sub>2</sub>]<sup>−</sup>, [N{(C<sub>3</sub>F<sub>7</sub>)C(4-(NO<sub>2</sub>)C<sub>6</sub>H<sub>4</sub>)N}<sub>2</sub>]<sup>−</sup>, [N{(C<sub>3</sub>F<sub>7</sub>)C(2-(CF<sub>3</sub>)C<sub>6</sub>H<sub>4</sub>)N}<sub>2</sub>]<sup>−</sup>, and
[N{(C<sub>3</sub>F<sub>7</sub>)C(2-F,6-(CF<sub>3</sub>)C<sub>6</sub>H<sub>3</sub>)N}<sub>2</sub>]<sup>−</sup> have been used as
supporting ligands
in copper(I) ethylene chemistry. [N{(C<sub>3</sub>F<sub>7</sub>)C(2-(NO<sub>2</sub>)C<sub>6</sub>H<sub>4</sub>)N}<sub>2</sub>]Cu(C<sub>2</sub>H<sub>4</sub>) (<b>7</b>), [N{(C<sub>3</sub>F<sub>7</sub>)C(4-(NO<sub>2</sub>)C<sub>6</sub>H<sub>4</sub>)N}<sub>2</sub>]Cu(C<sub>2</sub>H<sub>4</sub>) (<b>8</b>), [N{(C<sub>3</sub>F<sub>7</sub>)C(2-(CF<sub>3</sub>)C<sub>6</sub>H<sub>4</sub>)N}<sub>2</sub>]Cu(C<sub>2</sub>H<sub>4</sub>) (<b>9</b>), and [N{(C<sub>3</sub>F<sub>7</sub>)C(2-F,6-(CF<sub>3</sub>)C<sub>6</sub>H<sub>3</sub>)N}<sub>2</sub>]Cu(C<sub>2</sub>H<sub>4</sub>) (<b>10</b>) are easily isolable,
thermally stable solids
and display their ethylene proton and carbon resonances in the δ
3.68–3.48 and 85.2–87.6 ppm regions, respectively. X-ray
crystal structures reveal that <b>7</b>–<b>10</b> feature trigonal-planar copper sites and κ<sup>2</sup>-bonded,
U-shaped triazapentadienyl ligands. The Cu(I) carbonyl adducts [N{(C<sub>3</sub>F<sub>7</sub>)C(2-(NO<sub>2</sub>)C<sub>6</sub>H<sub>4</sub>)N}<sub>2</sub>]Cu(CO)(NCCH<sub>3</sub>) (<b>16</b>) and [N{(C<sub>3</sub>F<sub>7</sub>)C(4-(NO<sub>2</sub>)C<sub>6</sub>H<sub>4</sub>)N}<sub>2</sub>]Cu(CO)(NCCH<sub>3</sub>) (<b>17</b>) have also
been synthesized, and they have pseudotetrahedral copper sites. The
CO stretching frequencies of the compounds <b>16</b> and <b>17</b> and ethylene <sup>13</sup>C NMR chemical shift data of <b>7</b>–<b>10</b> suggest that these molecules have
rather acidic copper sites and weakly donating triazapentadienyl ligands
