Synthesis and catalytic applications of ruthenium(II)-phosphino-oxime complexes

In this work, the preparation of the first ruthenium complexes containing a phosphino-oxime ligand is presented. Thus, the reaction of cis-[RuCl2(DMSO)(4)] (3) with 2.4 equivalents of 2-Ph2PC6H4CH=NOH (1) in refluxing THF led to the clean formation of the octahedral ruthenium(II) derivative cis, cis, trans-RuCl2{kappa(2)-(P,N)-2-Ph2PC6H4CH=NOH}(2)] (5), whose structure was unambiguously confirmed by means of a single-crystal X-ray diffraction study. Complex 5 could also be synthesized from the reaction of the dimer [{RuCl(mu-Cl)(eta(6)-p-cymene)}(2)] (4) with an excess of 1 in refluxing toluene. Treatment of 4 with 2 equivalents of 1, in CH2Cl2 at r.t., allowed also the preparation of the half-sandwich Ru(II) derivative [RuCl{kappa(2)-(P,N)-2-Ph2PC6H4CH=NOH}(eta(6)-p-cymene)][PF6] (6). In addition, complexes 5 and 6 proved to be active catalysts for the rearrangement of aldoximes to primary amides, as well as for the alpha-alkylation/reduction of acetophenones with primary alcohols, with the former showing the best performances in both processes.