Rhenium Complexes Containing the Chiral Tridentate Ferrocenyl Ligand Pigiphos

2011-09-12T00:00:00Z (GMT) by Esteban Mejía Antonio Togni
The paramagnetic Re(III) complex [ReCl<sub>3</sub>(Pigiphos)] (<b>1</b>) ((<i>R</i>)-(<i>S</i>)-Pigiphos = bis{(<i>R</i>)-1-[(<i>S</i>)-2-(diphenylphosphino)ferrocenyl]ethyl}cyclohexylphosphine) is accessible from [ReCl<sub>3</sub>(NCMe)(PPh<sub>3</sub>)<sub>2</sub>] and the ligand Pigiphos. <b>1</b> reacts with an excess of NaBH<sub>4</sub>, affording the polyhydride complex [ReH<sub>5</sub>(Pigiphos)] (<b>2</b>), which was shown to be a classic polyhydride (NMR <i>T</i><sub>1</sub>(min) = 158 ms). This complex reacts readily with both Brønsted acids and hydride scavengers to give the corresponding cationic tetrahydride species, which was shown to be active in the catalytic hydrogenation of dimethyl itaconate.