Selenoquinones Stabilized by Ruthenium(II) Arene Complexes: Synthesis, Structure, and Cytotoxicity

A new series of monoselenoquinone and diselenoquinone π complexes, [(η 6 ‐ p ‐cymene)Ru(η 4 ‐C 6 R 4 SeE)] (R=H, E=Se ( 6 ); R=CH 3 , E=Se ( 7 ); R=H, E=O ( 8 )), as well as selenolate π complexes [(η 6 ‐ p ‐cymene)Ru(η 5 ‐C 6 H 3 R 2 Se)][SbF 6 ] (R=H ( 9 ); R=CH 3 ( 10 )), stabilized by arene ruthenium moieties were prepared in good yields through nucleophilic substitution reactions from dichlorinated‐arene and hydroxymonochlorinated‐arene ruthenium complexes [(η 6 ‐ p ‐cymene)Ru(C 6 R 4 XCl)][SbF 6 ] 2 (R=H, X=Cl ( 1 ); R=CH 3 , X=Cl ( 2 ); R=H, X=OH ( 3 )) as well as the monochlorinated π complexes [(η 6 ‐ p ‐cymene)Ru(η 5 ‐C 6 H 3 R 2 Cl)][SbF 6 ] 2 (R=H ( 4 ); R=CH 3 ( 5 )). The X‐ray crystallographic structures of two of the compounds, [(η 6 ‐ p ‐cymene)Ru(η 4 ‐C 6 Me 4 Se 2 )] ( 7 ) and [(η 6 ‐ p ‐cymene)Ru(η 4 ‐C 6 H 4 SeO)] ( 8 ), were determined. The structures confirm the identity of the target compounds and ascertain the coordination mode of these unprecedented ruthenium π complexes of selenoquinones. Furthermore, these new compounds display relevant cytotoxic properties towards human ovarian cancer cells.