title: Design, syntheses, and characterization of dioxo-molybdenum(VI) complexes with thiolate ligands: effects of intraligand NH...S hydrogen bonding.
abstract: Presence of the hydrogen bonding near a metal center can influence the properties of the complex. Here, we describe changes in redox and spectral properties in discrete dioxo-molybdenum centers coordinated by a single thiolato ligand that can support an intra-ligand hydrogen bond. We have utilized thiophenolato ligands that can harbor hydrogen bonding between the thiophenolato sulfur with an amide functionality creating either a five- or a six-membered ring. Methylation of the amide functionality removes the NH...S hydrogen bonding thus providing a basis for understanding the effect of hydrogen bonding. These thiophenolato ligands have been used in synthesizing dioxo-MoVI complexes of type Tp*MoO2(S-o-RC6H4), where R=CONHMe (), CONMe2 (), NHCOMe (), and N(Me)COMe (). The complexes have been characterized by NMR, infrared, and UV-visible spectroscopy. Spectroscopic data clearly indicate the presence of hydrogen bonding in both and , and stronger in , where hydrogen bonding stabilizes a five-membered ring. All complexes exhibit a Mo(VI)/Mo(V) redox couple and redox potentials are modulated by the nature of H-bonding. Compound with the electron-releasing N(Me)COMe group has the highest reduction potential and is more difficult to reduce.
authors.affiliation: Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, USA.
authors.forename: Raghvendra S
authors.initials: RS
authors.lastname: Sengar
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Miller
authors.forename: Partha
authors.initials: P
authors.lastname: Basu
mesh_terms: D000577:Amides / Q000737:chemistry*; D001665:Binding Sites; D015195:Drug Design; D004563:Electrochemistry; D006860:Hydrogen Bonding; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008982:Molybdenum / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D010100:Oxygen / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013455:Sulfur / Q000737:chemistry*
chemical_list: D000577:Amides; D008024:Ligands; D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D013455:Sulfur; D008982:Molybdenum; D010100:Oxygen