Sequential Protonation and Methylation of a Hydride−Osmium Complex
Containing a Cyclopentadienyl Ligand with a Pendant Amine Group
Miguel A. Esteruelas
Ana M. López
Enrique Oñate
Eva Royo
10.1021/ic0502933.s001
https://acs.figshare.com/articles/journal_contribution/Sequential_Protonation_and_Methylation_of_a_Hydride_Osmium_Complex_Containing_a_Cyclopentadienyl_Ligand_with_a_Pendant_Amine_Group/3284191
Complex OsH{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>NMe<sub>2</sub>}(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub> (<b>1</b>) reacts with 1 equiv of trifluoromethanesulfonic acid (HOTf) and
trifluoromethanesulfonic acid-<i>d</i><sub>1</sub> (DOTf) to produce the dihydride and hydride−deuteride complexes, [OsHE{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>NMe<sub>2</sub>}(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub>]OTf (E = H (<b>2</b>), D (<b>2-</b><b><i>d</i></b><b><sub>1</sub></b>)), respectively. Treatment of <b>2</b> and <b>2-</b><b><i>d</i></b><b><sub>1</sub></b> with a second equivalent
of HOTf gives [OsHE{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>NHMe<sub>2</sub>}(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub>][OTf]<sub>2</sub> (E = H (<b>3</b>), D (<b>3-</b><b><i>d</i></b><b><i><sub>1</sub></i></b>)) as a result of the protonation of
the nitrogen atom. While the hydride and deuteride ligands of <b>2</b>, <b>2-</b><b><i>d</i></b><b><sub>1</sub></b>,<b></b><b>3</b>, and <b>3-</b><b><i>d</i></b><b><sub>1</sub></b> do not undergo any H/D exchange
process with the solvent, in acetone-<i>d</i><sub>6</sub>, the NH proton of <b>3</b> and <b>3-</b><b><i>d</i></b><b><sub>1</sub></b> changes places with a deuterium atom of the
solvent to yield [OsHE{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>NDMe<sub>2</sub>}(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub>][OTf]<sub>2</sub> (E = H (<b>3-</b><b><i>Nd</i></b><b><sub>1</sub></b>), D (<b>3-</b><b><i>d</i></b><b><sub>2</sub></b>)). Complex <b>3-</b><b><i>Nd</i></b><b><sub>1</sub></b> can also be
obtained from the treatment of complex <b>2</b> with DOTf in dichloromethane. No exchange process between the hydride
and the ND positions in <b>3-</b><b><i>Nd</i></b><b><sub>1</sub></b> or between the deuteride and NH positions in <b>3-</b><b><i>d</i></b><b><sub>1</sub></b> has been observed. Treatment
of <b>3-</b><b><i>Nd</i></b><b><sub>1</sub></b> and <b>3-</b><b><i>d</i></b><b><sub>1</sub></b> with sodium methoxide results in a selective reaction of the base with the ammonium group to
regenerate <b>2</b> and <b>2-</b><b><i>d</i></b><b><sub>1</sub></b>, respectively. Complex <b>1</b> also reacts with methyl and methyl-<i>d</i><sub>3</sub> trifluoromethanesulfonate
(CH<sub>3</sub>OTf and CD<sub>3</sub>OTf, respectively) to give [OsH{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>NMe<sub>2</sub>CE<sub>3</sub>}(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub>]OTf (E = H (<b>4</b>), D (<b>4-</b><b><i>d</i></b><b><sub>3</sub></b>)) as a
result of the addition of the CE<sub>3</sub> (E = H, D) group to the nitrogen atom. Complex <b>4</b> has been characterized by an
X-ray diffraction analysis. It reacts with a second molecule of CH<sub>3</sub>OTf or CD<sub>3</sub>OTf to produce [ (<b>5</b>). Similarly, complex <b>4-</b><b><i>d</i></b><b><sub>3</sub></b> reacts with a second molecule of CH<sub>3</sub>OTf or
CD<sub>3</sub>OTf to yield (<b>5-</b><b><i>d</i></b><b><sub>3</sub></b>). In acetonitrile, complex <b>5</b>
evolves to an equilibrium mixture of the acetonitrile adducts [Os{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>NMe<sub>3</sub>}(NCCH<sub>3</sub>)(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub>][OTf]<sub>2</sub> (<b>7</b>)
and [Os{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>NMe<sub>3</sub>}(NCCH<sub>3</sub>)<sub>2</sub>(P<sup>i</sup>Pr<sub>3</sub>)][OTf]<sub>2</sub> (<b>8</b>). In methanol or methanol<i>-d</i><sub>4</sub>, complex <b>4 </b>is not stable and
loses trimethylamine to give the vinylcyclopentadienyl derivatives [OsHE(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>CHCH<sub>2</sub>)(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub>]OTf (E = H (<b>9</b>),
D (<b>9-</b><b><i>d</i></b><b><sub>1</sub></b>)) as a result of the protonation or deuteration of the metallic center and a subsequent Hofmann elimination.
Protonation of <b>4</b> with HOTf gives the dihydride−trimethylammonium derivative [OsH<sub>2</sub>{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>(CH<sub>2</sub>)<sub>2</sub>NMe<sub>3</sub>}(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub>][OTf]<sub>2</sub> (<b>10</b>). Treatment of <b>9</b> with sodium methoxide produces OsH(η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>CHCH<sub>2</sub>)(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub> (<b>11</b>).
2005-05-30 00:00:00
trifluoromethanesulfonic acid
CD 3 OTf
Pr
Complex
C 5 H 4
CH 2
NH
ND
nitrogen atom
CE
NMe
CH 3 OTf
NCCH
sodium methoxide results
1 changes places