Issue 34, 2016

Novel pyrazolylphosphite– and pyrazolylphosphinite–ruthenium(ii) complexes as catalysts for hydrogenation of acetophenone

Abstract

The new compounds and potential ligands 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiphenlyphosphinite (L1), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyldiethylphosphite (L2), 2-(3,5-di-tert-butyl-1H-pyrazol-1-yl)ethyl-diethylphosphite (L3) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiethylphosphite (L4) were prepared from the reaction of (3,5-(disubstituted)pyrazol-1H-yl)ethanol and the appropriate phosphine chloride. The phosphinite (L1) and phosphites (L2–L4) and 2-(3,5-diphenyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L5) were reacted with [Ru(p-cymene)Cl2]2 to afford the ruthenium(II) complexes [Ru(p-cymene)Cl2(L1)] (1), [Ru(p-cymene)Cl2(L2)] (2), [Ru(p-cymene)Cl2(L3)] (3), [Ru(p-cymene)Cl2(L4)] (4), and [Ru(p-cymene)Cl2(L5)] (5). All ruthenium complexes were characterized by a combination of NMR spectroscopy, elemental analysis and, in selected cases, by single crystal X-ray crystallography. Complexes 1–5 and [Ru(p-cymene)Cl2(L6)] (6) (prepared from 2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyldiphenylphosphinite (L6)) were investigated as catalysts for both transfer and molecular hydrogenation of acetophenone to 1-phenylethanol. At 80 °C the percent conversion of acetophenone in transfer hydrogenation was moderate to high over 10 h (42–87%); for molecular hydrogenation acetophenone, conversions were as high as 98% in 6 h.

Graphical abstract: Novel pyrazolylphosphite– and pyrazolylphosphinite–ruthenium(ii) complexes as catalysts for hydrogenation of acetophenone

Supplementary files

Article information

Article type
Paper
Submitted
30 May 2016
Accepted
01 Aug 2016
First published
01 Aug 2016

Dalton Trans., 2016,45, 13514-13524

Novel pyrazolylphosphite– and pyrazolylphosphinite–ruthenium(II) complexes as catalysts for hydrogenation of acetophenone

G. Amenuvor, C. Obuah, E. Nordlander and J. Darkwa, Dalton Trans., 2016, 45, 13514 DOI: 10.1039/C6DT02164F

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