Synthesis, structures, reactivity and catalytic activity of cyclometalated ruthenium phosphine and phosphinite complexes

Reactions of naphthyl and o-methylphenyl-substituted phosphines with [RuCl2(p-cymene)]2 resulted in corresponding phosphine-substituted ruthenium dichlorides (1a,b, and 3). When the reactions of aryl-substituted phosphines or phosphinite with [RuCl2(p-cymene)]2 were carried out in the presence of sodium acetate, aryl-substituted phosphines or phosphinite are cyclometalated to give corresponding five-membered metallacycle complexes (2a,b, and 4-6) via an intramolecular activation of C(sp2)−H or C(sp3)−H bond. Competition reaction indicates that the aromatic C(sp2)−H bond is more likely to be activated than C(sp3)−H bond under the same conditions, and five-membered ring is formed in preference to six-membered ring. Chemical reactivity of 2a,b, two representatives of cycloruthenated complexes, were explored, including conversion of 1a,b to 2a,b, substitution reaction of η6 arene ligand in 2a, synthesis of bis-phosphine complex starting from 2b, and reaction of 2a with diphenylacetylene. Besides, their catalytic activity on reduction of ketones by transfer hydrogenation was also tested. Molecular structures of nine compounds 1b, 2a, 4, 5, 6, 7, 8a, 9, and 10 were determined by X-ray diffraction.

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