Ruthenium halide complexes as N-alkylation catalysts

A range of ruthenium-arene compounds with chloride, bromide or iodide ligands were prepared and tested as catalysts for the homogeneous redox neutral alkylation of tert-butylamine with phenethyl alcohol, and compared to the previously reported catalyst [RuCl2(p-cymene)]2, in the presence of the diphosphine 1,1′-bis(diphenylphosphino)ferrocene (dppf). The best catalytic activities were obtained with ruthenium iodide compounds. The formation of either [RuX(p-cymene)(dppf)][X] or [(RuX2(p-cymene)) 2(dppf)] (X = halide) under the catalytic conditions employed was investigated.