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

Abstract

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{η 2-N(O)C 10H 6O} 2(CO) 2] 1a and cis-[Ru{η 2-N(O)C 10H 6O} 2(CO) 2] 1b. Compound 1b could be converted to 1a quantitatively in acidic media. Reaction of 1a with acetylpyridine in the presence of trimethylamine N-oxide afforded trans-[Ru{η 2-N(O)C 10H 6O} 2{NC 5H 4C(O)CH 3}(CO)] 2 in which one of the carbonyls was replaced by an acetylpyridine moiety. Similarly, complex 3, trans-[Ru{η 2-N(O)C 10H 6O} 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(μ-η 3-ONC 10H 6O) 2(CO) 8] 4 and [Ru 3(μ-η 2-N(H)C 10H 6O) {μ-η 2-N(H)C 10H 4(O)NOC 10H 6}(CO) 8] 5 were isolated in addition to 1a and 1b. 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 μ-η 3 and a μ-η 2-manner respectively.