Syntheses and molecular structures of ruthenium carbonyl complexes containing 1,2-naphthoquinone-1-oximate ligands

The reaction of [Ru-3(CO)(12)] with 1-nitroso-2-naphthol (referred to as 1,2-naphthoquinone-1-oxime, Hnqo) in tetrahydrofuran (thf) at room temperature gave two isomeric mononuclear complexes, trans-[Ru{eta(2)-N(O)C10H6O}(2)(CO)(2)] la and cis-[Ru{eta(2)-N(O)C10H6O}(2)(CO)(2)] 1b. Compound Ib could be converted to la quantitatively in acidic media. Reaction of la with acetylpyridine in the presence of trimethylamine N-oxide afforded trans-[Ru{eta(2)-N(O)C10H6O}(2){NC5H4C(O)CH3}(CO)] 2 in which one of the carbonyls was replaced by an acetylpyridine moiety. Similarly, complex 3, trans-[Ru{eta(2)-N(O)C10H6O}(2)(NCMe)(CO)] was also obtained in high yield if acetonitrile was used instead of the acetylpyridine. When the reaction of [Ru-3(CO)(12)] and 1-nitroso-2-naphthol was carried out in refluxing thf for 1 h, two minor products [Ru-3(mu-eta(3)-ONC10H6O)(2)(CO)(8)] 4 and [Ru-3{mu-eta(2)-N(H)C10H6O}{mu-eta(2)-N(H)C10H4(O)NOC10H6}(CO)(8)] 5 were isolated in addition to la and Ib. Clusters 4 and 5 consisted of an open triruthenium metal core with the two nqo ligands (in 4) and two quinone-imine type ligands (in 5) bridging the open edge in a mu-eta(3) and a mu-eta(2)-manner respectively.