Synthesis,spectroscopic characterization and DFT study of dinuclear ruthenium sawhorse-type complexes derived from the reaction of trinuclear aggregates and (Z)-5-arylidenerhodanines |
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Authors: | Katherine Paredes-Gil Esperanza Galarza David L Cedeño Braulio Insuasty Rodrigo Abonia |
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Institution: | 1. Relativistic Molecular Physics (ReMoPh) Group, Facultad de Ciencias Exactas, Universidad Andres Bello, Santiago, Chile;2. Grupo de Investigación en Síntesis Organometálica y Catálisis, GISIOMCA, Departamento de Química, Universidad del Valle, Cali, Colombia;3. Facultad de Ciencias, Departamento de Química, Universidad de Chile, Santiago, Chileesperanza.galarza@correounivalle.edu.co;5. Grupo de Investigación en Síntesis Organometálica y Catálisis, GISIOMCA, Departamento de Química, Universidad del Valle, Cali, Colombia;6. Department of Chemistry, Illinois State University, Normal, IL, USA;7. Grupo de Investigación de Compuestos Heterocíclicos, Departamento de Química, Universidad del Valle, Cali, Colombia |
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Abstract: | The synthesis of dinuclear ruthenium sawhorse-type complexes Ru2(μ-ArCH:Rhod)2(CO)4]n 12a–e and Ru2(ArCH:Rhod)2(μ-ArCH:Rhod)2(CO)4] 13a–e through reaction of Ru3(CO)10(NCMe)2] and Ru3(CO)12] and the corresponding (Z)-5-arylidenerhodanines (ArCH:Rhod) 10a–e, respectively, are reported. These complexes are arranged in a sawhorse structure in which two bridged (Z)-5-arylidenerhodanines coordinate to the metals using sulfur and nitrogen of the rhodanine ring. A Density Functional Theory method was used to gain insight into the polymerization process by calculating dimerization Gibbs energies (ΔGdim). Values between ?10.7 and ?5.3 kcal mol?1 indicate that dimerization is a spontaneous process. A reaction pathway for formation of the sawhorse compounds Ru2(μ-ArCH:Rhod)2(CO)4] was calculated and the rate-determining step for the mechanism is coordination of a second (Z)-5-arylidenerhodanine ligand with activation energies between 41.1 and 47.8 kcal mol?1. In order to understand the apparent thermodynamic favorability of the fragmentation step, we calculated the fragmentation energy (ΔEFrag) for the key intermediate and its energetic contributors, the interaction energy, ΔEint and the reorganization energy, ΔEreorg. Low values of ΔEFrag imply that the fragmentation is thermodynamically facile. Large values of ΔEint are countered by opposite and large values of ΔEreorg which indicate that the cleavage of the trimetallic intermediate aggregate is determined by the nature of the ligand and the balance between its interaction with the metal and the extent of structural reorganization. |
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Keywords: | Sawhorse-type complexes ruthenium cluster carbonyls DFT-mechanism fragmentation energy |
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