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Preparation of Neutral <i>trans - cis</i> [Ru(O<sub>2</sub>CR)<sub>2</sub>P<sub>2</sub>(NN)], Cationic [Ru(O<sub>2</sub>CR)P<sub>2</sub>(NN)](O<sub>2</sub>CR) and Pincer [Ru(O<sub>2</sub>CR)(CNN)P<sub>2</sub>] (P = PPh<sub>3</sub>, P<sub>2</sub> = diphosphine) Carboxylate Complexes and their Application in the Catalytic Carbonyl Compounds Reduction
11
Citations
63
References
2021
Year
The diacetate complexes <i>trans</i>-[Ru(κ<sup>1</sup>-OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>(NN)] (NN = ethylenediamine (en) (<b>1</b>), 2-(aminomethyl)pyridine (ampy) (<b>2</b>), 2-(aminomethyl)pyrimidine (ampyrim) (<b>3</b>)) have been isolated in 76-88% yield by reaction of [Ru(κ<sup>2</sup>-OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>] with the corresponding nitrogen ligands. The ampy-type derivatives <b>2</b> and <b>3</b> undergo isomerization to the thermodynamically most stable cationic complexes [Ru(κ<sup>1</sup>-OAc)(PPh<sub>3</sub>)<sub>2</sub>(NN)]OAc (<b>2a</b> and <b>3a</b>) and <i>cis</i>-[Ru(κ<sup>1</sup>-OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>(NN)] (<b>2b</b> and <b>3b</b>) in methanol at RT. The <i>trans</i>-[Ru(κ<sup>1</sup>-OAc)<sub>2</sub>(P<sub>2</sub>)<sub>2</sub>] (P<sub>2</sub> = dppm (<b>4</b>), dppe (<b>5</b>)) compounds have been synthesized from [Ru(κ<sup>2</sup>-OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>] by reaction with the suitable diphosphine in toluene at 95 °C. The complex <i>cis</i>-[Ru(κ<sup>1</sup>-OAc)<sub>2</sub>(dppm)(ampy)](<b>6</b>) has been obtained from [Ru(κ<sup>2</sup>-OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>] and dppm in toluene at reflux and reaction with ampy. The derivatives <i>trans</i>-[Ru(κ<sup>1</sup>-OAc)<sub>2</sub>P<sub>2</sub>(NN)] (<b>7</b>-<b>16</b>; NN = en, ampy, ampyrim, 8-aminoquinoline; P<sub>2</sub> = dppp, dppb, dppf, (<i>R</i>)-BINAP) can be easily synthesized from [Ru(κ<sup>2</sup>-OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>] with a diphosphine and treatment with the NN ligands at RT. Alternatively these compounds have been prepared from <i>trans</i>-[Ru(OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>(NN)] by reaction with the diphosphine in MEK at 50 °C. The use of (<i>R</i>)-BINAP affords <i>trans</i>-[Ru(κ<sup>1</sup>-OAc)<sub>2</sub>((<i>R</i>)-BINAP)(NN)] (NN = ampy (<b>11</b>), ampyrim (<b>15</b>)) isolated as single stereoisomers. Treatment of the ampy-type complexes <b>8</b>-<b>15</b> with methanol at RT leads to isomerization to the cationic derivatives [Ru(κ<sup>2</sup>-OAc)P<sub>2</sub>(NN)]OAc (<b>8a</b>-<b>15a</b>; NN = ampy, ampyrim; P<sub>2</sub> = dppp, dppb, dppf, (<i>R</i>)-BINAP). Similarly to <b>2</b>, the dipivalate <i>trans</i>-[Ru(κ<sup>1</sup>-OPiv)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>(ampy)] (<b>18</b>) is prepared from [Ru(κ<sup>2</sup>-OPiv)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>] (<b>17</b>) and ampy in CHCl<sub>3</sub>. The pincer acetate [Ru(κ<sup>1</sup>-OAc)(CNN<sup>OMe</sup>)(PPh<sub>3</sub>)<sub>2</sub>] (<b>19</b>) has been synthesized from [Ru(κ<sup>2</sup>-OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>] and HCNN<sup>OMe</sup> ligand in 2-propanol with NEt<sub>3</sub> at reflux. In addition, the dppb pincer complexes [Ru(κ<sup>1</sup>-OAc)(CNN)(dppb)] (CNN = AMTP (<b>20</b>), AMBQ<sup>Ph</sup> (<b>21</b>)) have been obtained from [Ru(κ<sup>2</sup>-OAc)<sub>2</sub>(PPh<sub>3</sub>)<sub>2</sub>], dppb, and HAMTP or HAMBQ<sup>Ph</sup> with NEt<sub>3</sub>, respectively. The acetate NN and pincer complexes are active in transfer hydrogenation with 2-propanol and hydrogenation with H<sub>2</sub> of carbonyl compounds at S/C values of up to 10000 and with TOF values of up to 160000 h<sup>-1</sup>.
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