Ruthenocenyl phosphinated chalcones and their Pt(II) and Pd(II) complexes: Usual bidentate [PO] and unusual tridentate [PCO] coordination

• Published in: Inorganica Chimica Acta 2019-11, Vol.497, p.119074, Article 119074
• Main Authors: Anzaldo, Bertin, Sharma, Pankaj, Gutiérrez Pérez, Rene, Villamizar C, Claudia P., Barquera-Lozada, José E., Toscano, Alfredo, Gaviño, Rubén, Portillo, Oscar
• Format: Article
• Language: English
• Subjects: Acetonitrile; Bonding strength; Chelation; Coordination compounds; Crystal structure; Electrochemistry; Hydrogen bonds; Ligands; NMR; Nuclear magnetic resonance; Organic chemistry; Palladium; Platinum; Quantum chemistry; Ruthenocenyl chalcones; Stereochemistry; Tridentate η1 coordination
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2019.119074

New ruthenocenyl phosphinated chalcone ligands and their respective Pt(II) and Pd(II) complexes [MCl(κ3-PCO)] [M = Pt(II)/Pd(II)] were synthesized where the ligands coordinate in a tridentate fashion, and present an unusual η1 coordination at the double bond by activation of Csp2-H bond. During the isolation of Pt(II) (6) complex, a new unstable platinum phosphino-alkene complex (7) was also isolated as a minor product and the molecular structure was determined. In this complex, the chalcone ligand (2) coordinates in usual bidentate fashion through phosphorus atom and η2 coordination at the double bond. Solution NMR and X-ray crystal structure of chalcone confirm the presence of (E)-stereochemistry at the double bond and s-cis conformation of the enone portion and complexes show square planar geometry around the metal center. [Display omitted] •New ruthenocenyl phosphinated chalcones.•Pt(II) and Pd(II) complexes [MCl(κ3-PCO)] with tridentate ligation of chalcones.•An unusual η1 coordination at the double bond by activation of C–H bond.•New unstable platinum phosphino-alkene complex [PtCl2(κ2-PO)] as a minor product.•Determination of structure by 1D & 2D 1H, 13C and 31P NMR spectra & X-ray analyses.•Quantum chemical calculations for η1 coordinated and η2 coordinated complex. New ruthenocenyl phosphinated chalcones β-(2′-diphenylphosphinophenyl)-acrylruthenocene CpRu(C5H4)C(O)–CHCHC6H4PPh2 (2) and β-(2′-ditolylphosphinophenyl)-acrylruthenocene CpRu(C5H4)C(O)–CHCHC6H4P(tolyl)2 (3) and their Pt(II) and Pd(II) complexes [MCl(κ3-PCO)] (4)–(6) were synthesized as the predominant product, where chalcones coordinate in a tridentate fashion to the metal center and present an unusual η1 coordination at the double bond by activation of C–H bond. During the isolation of Pt(II) (6) complex, a new unstable platinum phosphino-alkene complex (7) [PtCl2(κ2-PO)]was also isolated as a minor product. The X-ray crystal structure of (7) confirms that ligand (2) acts as bidentate ligand and coordinates through phosphorus and η2 double bond ligation to Pt(II) metal. Solution NMR and X-ray crystal structure of chalcone confirm the presence of (E)-stereochemistry at the double bond and s-cis conformation of the enone portion and complexes show square planar geometry around the metal center. Complex (7) decomposes to complex (6) and the oxidized product of ruthenocenyl phosphinated chalcone. Quasi-reversible electrochemistry was found for the ruthenocenyl center in these compounds in