2 research outputs found
Reactivity of Tuck-over Titanium Oxo Complexes with Isocyanides
No full textThe reactivity of
the âtuck-overâ species [Ti<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Â(CH<sub>2</sub>Ph)<sub>3</sub>Â(ÎŒ-η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>CH<sub>2</sub>-Îș<i>C</i>)Â(ÎŒ-O)]
(<b>1</b>) and [Ti<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Â(CH<sub>2</sub>CMe<sub>3</sub>)Â(ÎŒ-η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>CH<sub>2</sub>-Îș<i>C</i>)Â(ÎŒ-CH<sub>2</sub>CMe<sub>2</sub>CH<sub>2</sub>)Â(ÎŒ-O)] (<b>2</b>) toward isocyanides has been
examined both synthetically and theoretically. Treatment of <b>1</b> with the isocyanides RNC, R = Me<sub>3</sub>SiCH<sub>2</sub>, 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub>, <i>t</i>Bu, <i>i</i>Pr, leads to a series of η<sup>2</sup>-iminoacyl species (<b>3</b>â<b>6</b>) where the
molecule of isocyanide inserts into one of the terminal metalâalkyl
bonds. The analogous reaction of the âtuck-overâ metallacycle
species <b>2</b> with 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub>NC and <i>t</i>BuNC results in the initial insertion of
one isocyanide into the terminal Tiâalkyl bond to form the
iminoacyl complexes <b>7</b> and <b>8</b>, followed by
a second insertion into the metallacycle moiety to generate <b>9</b>, in the case of <i>tert</i>-butylisocyanide. DFT
calculations support the selective reactivity observed experimentally
with a kinetic and thermodynamic preference for RNC insertion on the
terminal alkyl groups bound to both metallic centers over the alternative
insertion on the âtuck-overâ ligand
Reactivity of Tuck-over Titanium Oxo Complexes with Isocyanides
Get PDFThe reactivity of
the âtuck-overâ species [Ti<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Â(CH<sub>2</sub>Ph)<sub>3</sub>Â(ÎŒ-η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>CH<sub>2</sub>-Îș<i>C</i>)Â(ÎŒ-O)]
(<b>1</b>) and [Ti<sub>2</sub>(η<sup>5</sup>-C<sub>5</sub>Me<sub>5</sub>)Â(CH<sub>2</sub>CMe<sub>3</sub>)Â(ÎŒ-η<sup>5</sup>-C<sub>5</sub>Me<sub>4</sub>CH<sub>2</sub>-Îș<i>C</i>)Â(ÎŒ-CH<sub>2</sub>CMe<sub>2</sub>CH<sub>2</sub>)Â(ÎŒ-O)] (<b>2</b>) toward isocyanides has been
examined both synthetically and theoretically. Treatment of <b>1</b> with the isocyanides RNC, R = Me<sub>3</sub>SiCH<sub>2</sub>, 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub>, <i>t</i>Bu, <i>i</i>Pr, leads to a series of η<sup>2</sup>-iminoacyl species (<b>3</b>â<b>6</b>) where the
molecule of isocyanide inserts into one of the terminal metalâalkyl
bonds. The analogous reaction of the âtuck-overâ metallacycle
species <b>2</b> with 2,6-Me<sub>2</sub>C<sub>6</sub>H<sub>3</sub>NC and <i>t</i>BuNC results in the initial insertion of
one isocyanide into the terminal Tiâalkyl bond to form the
iminoacyl complexes <b>7</b> and <b>8</b>, followed by
a second insertion into the metallacycle moiety to generate <b>9</b>, in the case of <i>tert</i>-butylisocyanide. DFT
calculations support the selective reactivity observed experimentally
with a kinetic and thermodynamic preference for RNC insertion on the
terminal alkyl groups bound to both metallic centers over the alternative
insertion on the âtuck-overâ ligand
