Protonation of pi-alkene-rhodium(I) complexes leads to sigma-alkyl-rhodium(III) - an NMR study
Artikel i vetenskaplig tidskrift, 1998

The reaction of Rh(beta-diketonato)(alkene)(2) complexes with CF3SO3H in THF gives Rh(beta-diketonato)(alkyl) species when the alkene is ethylene, cis-butene or 5-methylene-cycloheptene whereas 1,5-cyclooctadiene complexes are unreactive. The reaction was followed by means of NMR-spectroscopy at low temperature and the products were characterized in solution by 2D-NMR techniques. Three possible reaction mechanisms are discussed: ligand assisted proton transfer, hydride transfer and direct protonation of the alkene. The Rh(III)ethyl species are stable against degradation by beta-hydride elimination. However, Rh(III)(beta-diketonato)(n-butyl) complexes lose butene rapidly when ethylene is added and Rh(beta-diketonato)(ethyl) complexes are formed. A mechanism preventing the formation of higher oligomers is proposed, where beta-hydride elimination is followed by rapid alkene exchange and hydride re-insertion. (C) 1998 Elsevier Science S.A. All rights reserved.

homonuclear

energetics

palladium(ii)

polymerization

spectroscopy

platinum(ii)

rhodium(i)

resolution

ethylene

exchange kinetics

Författare

Lars Öhrström

Institutionen för oorganisk kemi

S. Stromberg

J. Glaser

K. Zetterberg

Journal of Organometallic Chemistry

Vol. 558 123-130

Ämneskategorier

Kemi