Dissolution of [RhCl(PPh3)3] in the ionic liquid, 1-ethyl-3-methyl imidazolium chloroaluminate(III), and its reaction with H2.: The stabilization of Rh(I) species in an ionic liquid

The solution of [RhCl(PPh3)(3)] in acidic 1-ethyl-3-methylimidazolium chloroaluminate(III) ionic liquid (AlCl3 molar fraction. x(AlCl3) 0.67) was investigated by H-1 and P-31{H-1} NMR. One triphenyl phosphine is lost from the complex and is protonated in the acidic media, and cis-[Rh(PPh3)(2)ClX], (2), where X is probably [AlCl4](-), is formed. On, standing, 2 is converted to trans-[Rh(H)(PPh3)(2)X]. (3). The reaction of 2 and H-2 also produces trans-[Rh(H)(PPh3)(2)X], (3) H-1 and P-31{H-1} NMR support the suggestion that a weak ligand such as [AlCl4](-) present in solution may interact with the metal centre. When [RhCl(PPh3)(3)] is dissolved in CH2Cl2/AlCl3/HCl for comparison, two exchanging isomers of what is probably [RhH{(mu-Cl)(2)AlCl2}{(mu-Cl)AlCl3}(PPh3)(2)]. (6) and (7), are formed. (C) 2002 Published by Elsevier Science B.V.