title: Cycloruthenated complexes from imine-based heterocycles: synthesis, characterization, and reactivity toward alkynes.
abstract: Novel cycloruthenated complexes 2 a-c, 4 a-c, and 6 a, b based on heteroaromatic cores have been synthesized by reaction of a series of heterocycle-based imines with [{RuCl(η(6)-p-cymene)}(2)(μ-Cl)(2)] and Cu(OAc)(2). This approach has proved efficient for the cyclometalation of thiophene, benzothiophene, furan, benzofuran, pyrrole, and indole derivatives. In addition, even a double cyclometalation process over the same heterocyclic ring is possible, yielding unprecedented bimetallic complexes. These ruthenacycles react with 3-hexyne through an unexpected pathway, which involves the coupling of the original imino heterocycle and acetylene followed by dearomatization to afford fused hetero-hydropyridyl ligands bonded to the {Ru(p-cymene)} organometallic moiety (i.e., 7 a-c and 8 a-c). These complexes represent, as far as we know, the first examples of this type of compound within the context of cyclometalation, and an exhaustive analysis of their structure was carried out in solution and solid state. Furthermore, these unique species react with CuCl(2), which promotes the rearomatization and the release of highly valuable aromatic fused bis-heterocycles (i.e., 9 a-c, 10 a-c, 11 a, and 12 a/12 a'), providing a novel and appealing synthetic route to this extraordinary family of molecules.
authors.affiliation: Departamento de Activación de enlaces por complejos metálicos Instituto de Síntesis Química y Catálisis Homogénea, CSIC-Universidad de Zaragoza, Pedro Cerbuna 12, 50009 Zaragoza, Spain.
authors.forename: Luciano
authors.initials: L
authors.lastname: Cuesta
authors.forename: Tatiana
authors.initials: T
authors.lastname: Soler
authors.forename: Esteban P
authors.initials: EP
authors.lastname: Urriolabeitia
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D000480:Alkynes; D006571:Heterocyclic Compounds; D007097:Imines; D009942:Organometallic Compounds; D012428:Ruthenium