Synthesis of the double spiked µ5-sulfide pentanuclear clusters using thermic reactions of Ru3-mercaptopyridine complexes

• Published in: Journal of molecular structure 2025-02, Vol.1321, p.140247, Article 140247
• Main Authors: Zuno-Cruz, Francisco J., Sánchez-Cabrera, Gloria, Cruz-Acosta, Alfonso, Rosales-Hoz, María J.
• Format: Article
• Language: English
• Subjects: Cluster; Diphosphine; Pentanuclear; Ruthenium; Sulfide
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2024.140247

•The thermolysis reaction of trinuclear diphosphine Ru3-mercaptopyridine clusters resulted in higher nuclearity compounds.•The novelty isostructural clusters [Ru5(CO)11(μ-H)(μ5-S){μ-κ2N,C-NC5H3(R)})(μ-κ2P2-dppm)2] were found by XRD and NMR experiments.•A C-S bond rupture gave a pentanuclear ruthenium core in a double-spiked structure with a μ5-sulfide group.•The cluster formation involves the coordination of an orthometallated pyridine fragment toward a Ru-Ru bond with a μ-hydride ligand formation.•Two dppm ligands are μ-κ2 coordinated toward the Ru3-fragment and to the spike in the pentanuclear clusters. The treatment of [Ru3(CO)10(μ-dppm)] with 6-methyl-2-mercaptopyridine (1) or 5-trifluoromethyl-2-mercaptopyridine (2) in refluxing THF for 10 h results in the formation of μ5 sulfide-capped pentanuclear clusters [Ru5(CO)11(μ-H)(μ5-S){μ-κ2N,C-NC5H3(R)})(μ-κ2P2-dppm)2] (R = CH3, 3a, 3a'; R=CF3, 3b,3b') respectively. These compounds exhibit unique structural features, with a μ5-S capped binding trinuclear and dinuclear fragments. The mercaptopyridine ligands undergo S-C bond scission, forming an orthometalated pyridine ligand coordinated to a Ru-Ru bond with a concomitant μ-hydride ligand formation. The structures also feature two dppm ligands, one in the Ru-Ru, which bears the μ-H, and the other bridging the Ru-Ru bond with the orthometallated pyridine. In solution, linkage isomers were observed; they differ in the coordination position of the orthometallated pyridine bonded to the same Ru-Ru bond. A single-crystal X-ray diffraction study confirmed the molecular structures of compounds 3a and 3b. NMR, IR, and HRMS were also carried out. Isostructural linkage isomers of high nuclearity [Ru5(CO)11(μ-H)(μ5-S){μ-κ2N,C-NC5H3(R)})(μ-κ2P2-dppm)2] (R = CH3, 3a, 3a'; R=CF3, 3b, 3b') were prepared from the thermolysis reaction of [Ru3(CO)10(μ-dppm)] (1) with substituted 2-mercaptopyridine. The single-crystal XRD studies of 3a and 3b revealed a novelty open pentanuclear ruthenium core in a double-spiked structure, having a μ5-sulfide group formed by C-S bond rupture. The cluster formation involves an orthometallated pyridine fragment coordinated toward a Ru-Ru bond in two orientations with a concomitant μ-hydride ligand formation. Two dppm ligands are coordinated toward the Ru3 and Ru2 fragments in the pentanuclear clusters. The condensation reaction of the ruthenium fragments favors 80 valence electron clusters. RMN, IR, and HRMS were also carried out for a full char