| Summary: | In this work, the covalent immobilization of two ruthenium(II) complexes, i.e., [Ru<sup>II</sup>Cl (bpea){(S)(-)(BINAP)}](BF<sub>4</sub>), <b>1,</b> and [Ru<sup>II</sup>Cl(bpea)(DPPE)](BF<sub>4</sub>), <b>2</b>, where BINAP = 2,2’-bis(diphenylphosphino)-1,1’-binaphthyl and DPPE = 1,2-bis(diphenylphosphino)ethane, have been obtained (AlPO<sub>4</sub>-Sepiolite@<b>1</b> and AlPO<sub>4</sub>-Sepiolite@<b>2</b>) by using a N-tridentate ligand N,N-bis-(2-pyridylmethyl)ethylamine (bpea), linked to an amorphous AlPO<sub>4</sub>-Sepiolite (20/80) inorganic support. This AlPO<sub>4</sub>-sepiolite support is able to immobilize the double amount of ruthenium complex (1.65%) than the amorphous AlPO<sub>4</sub> (0.89%). Both heterogenized complexes have been assessed as catalysts in the liquid phase hydrogenation of several substrates with carbonyl and/or olefinic double bonds using methanol as solvent, attaining good catalytic activity and high enantioselectivity (99%). The highest Turn Over Number (TON) value (748.6) was obtained over the [Ru<sup>II</sup> Cl (bpea)(DPPE)](BF<sub>4</sub>) <b>2</b> catalyst, although the [Ru<sup>II</sup>Cl(bpea){(S)(-)(BINAP)}](BF<sub>4</sub>) <b>1</b> exhibits better reusability. In fact, the [Ru<sup>II</sup>Cl(bpea){(S)(-)(BINAP)}](BF<sub>4</sub>) immobilized on AlPO<sub>4</sub>-Sepiolite maintained the activity throughout 14 successive runs. Furthermore, some findings on hydrogenation mechanisms of the α,β-unsaturated carbonyl compounds over Ru catalysts have been also obtained.
|
|---|