10.1021/om9802156.s001
Peter J. Stewart
Peter J.
Stewart
Alexander J. Blake
Alexander J.
Blake
Philip Mountford
Philip
Mountford
New Titanium Complexes Containing an
Amidinate−Imide Supporting Ligand Set:
Cyclopentadienyl, Alkyl, Borohydride, Aryloxide, and
Amide Derivatives
American Chemical Society
1998
Bu t
Activation parameters
chloride metathesis reactions
benzamidinate ligands
LiC 5 H 5
py
Amide Derivatives
New Titanium Complexes Containing
SiMe 3
η 3
PhC
LiBH 4
LiCH 2 SiMe 3
1998-07-02 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/New_Titanium_Complexes_Containing_an_Amidinate_Imide_Supporting_Ligand_Set_Cyclopentadienyl_Alkyl_Borohydride_Aryloxide_and_Amide_Derivatives/3782286
A range of chloride metathesis reactions of the monomeric titanium <i>N,N</i>‘-bis(trimethylsilyl)benzamidinato−imido complexes [Ti(NBu<sup>t</sup>){(4-C<sub>6</sub>H<sub>4</sub>R)C(NSiMe<sub>3</sub>)<sub>2</sub>}Cl(py)<sub>2</sub>] (R = H (<b>1</b>) or OMe
(<b>2</b>)) are described. Thus, reaction of <b>1</b> or <b>2</b> with LiC<sub>5</sub>H<sub>5</sub> gave the half-sandwich compounds
[Ti(NBu<sup>t</sup>){(4-C<sub>6</sub>H<sub>4</sub>R)C(NSiMe<sub>3</sub>)<sub>2</sub>}(η-C<sub>5</sub>H<sub>5</sub>)] (R = H (<b>3</b>) or OMe (<b>4</b>)). Reaction of <b>1</b> with LiCH<sub>2</sub>SiMe<sub>3</sub> or LiCH(SiMe<sub>3</sub>)<sub>2</sub> gave the 14-electron, first fully characterized group 4 imido−alkyl
derivatives [Ti(NBu<sup>t</sup>){PhC(NSiMe<sub>3</sub>)<sub>2</sub>}{CH(R)SiMe<sub>3</sub>}(py)] (R = H (<b>5</b>) or SiMe<sub>3</sub> (<b>6</b>)). For
comparative purposes, the 16-electron half-sandwich imido−alkyl complex [Ti(NBu<sup>t</sup>)(ηC<sub>5</sub>Me<sub>5</sub>)(CH<sub>2</sub>SiMe<sub>3</sub>)(py)] (<b>7</b>) was prepared from LiCH<sub>2</sub>SiMe<sub>3</sub> and [Ti(NBu<sup>t</sup>)(η-C<sub>5</sub>Me<sub>5</sub>)Cl(py)].
Reaction of <b>1</b> with LiBH<sub>4</sub> gave the η<sup>3</sup>-borohydride derivative [Ti(NBu<sup>t</sup>){PhC(NSiMe<sub>3</sub>)<sub>2</sub>}(η<sup>3</sup>-BH<sub>4</sub>)(py)] (<b>8</b>), while treatment of <b>1</b> with LiN(SiMe<sub>3</sub>)<sub>2</sub>, LiO-2,6-C<sub>6</sub>H<sub>3</sub>R<sub>2</sub> (R = Me or Bu<sup>t</sup>), or
LiPhC(NSiMe<sub>3</sub>)<sub>2</sub> gave the corresponding aryloxide, amide, or bis(benzamidinate) titanium
imido complexes [Ti(NBu<sup>t</sup>){PhC(NSiMe<sub>3</sub>)<sub>2</sub>}{N(SiMe<sub>3</sub>)<sub>2</sub>}(py)] (<b>9</b>), [Ti(NBu<sup>t</sup>){PhC(NSiMe<sub>3</sub>)<sub>2</sub>}(O-2,6-C<sub>6</sub>H<sub>3</sub>R<sub>2</sub>)(py)] (R = Me (<b>10</b>) or Bu<sup>t</sup> (<b>11</b>)), or [Ti(NBu<sup>t</sup>){PhC(NSiMe<sub>3</sub>)<sub>2</sub>}<sub>2</sub>(py)] (<b>13</b>).
Activation parameters for the concerted, restricted rotation of the aryloxide and benzamidinate ligands in <b>11</b> are reported and point to a dissociatively activated mechanism. The
X-ray structures of <b>5</b> and <b>7</b> have been determined.