Selective and Reversible Base-Induced Elimination of a Ruthenium Dithioether Yields a Vinyl Metallosulfonium Complex

• Published in: Inorganic chemistry Vol. 51; no. 14; pp. 7913 - 7920
• Main Authors: Chauhan, Rajat, Mashuta, Mark S, Grapperhaus, Craig A
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 16-07-2012
• Subjects: Magnetic Resonance Spectroscopy; Models, Molecular; Molecular Structure; Organometallic Compounds - chemical synthesis; Organometallic Compounds - chemistry; Oxidation-Reduction; Quantum Theory; Ruthenium - chemistry; Sulfhydryl Compounds - chemistry
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic300983x

Chemical oxidation of tris(2-diphenylphosphinebenzenethiolato)ruthenate(II) [Ru-1] – with ferrocenium hexafluorophosphate in the presence of ethylene yields [(2-diphenylphosphinebenzenethiolato)(ethane-1,2-diylbis(thio-2,1-phenylene)diphenylphosphine)ruthenium(II)] hexafluorophosphate, [Ru-1·C 2 H 4 ]PF 6 , from addition of the alkene across cis sulfur sites. The [Ru-1·C 2 H 4 ] + complex displays a single redox couple at +794 mV versus ferrocenium/ferrocene. 1H NMR of [Ru-1·C 2 H 4 ] + displays ethylene resonances at δ = 1.29 (td, 1H), 1.59 (td, 1H), 2.78 (dd, 1H), and 3.03 (dd, 1H). In the presence of base [Ru-1·C 2 H 4 ] + is selectively deprotonated at the pseudoequatorial proton on the carbon α to the sulfur trans to phosphorus, yielding the vinyl metallosulfonium derivative [Ru-1·C 2 H 3 ]. 1H and 31P NMR spectra of [Ru-1·C 2 H 3 ] are temperature dependent, associated with inversion of the sulfur lone pair at the vinyl metallosulfonium. The activation energy for the fluxional process calculated using density functional theory (B3LYP/LANL2DZ+6-31g) of 14.36 kcal/mol is consistent with the experimentally determined value of 13.08 kcal/mol. The complex [Ru-1·C 2 H 3 ] crystallizes as yellow blocks in the triclinic space group P-1 with unit cell dimensions of a = 11.2718(5) Å, b =12.0524(3) Å, c = 23.6075(10) Å, α = 101.715(3)°, β = 98.154(4)°, and γ = 105.209(3)°. Addition of hydrochloric acid to [Ru-1·C 2 H 3 ] regenerates [Ru-1·C 2 H 4 ] + . Addition of DCl confirms the selectivity of this reverse reaction.