Electron Exchange Involving a Sulfur-Stabilized Ruthenium Radical Cation

Abstract

Half-sandwich Ru(II) amine, thiol, and thiolate complexes were prepared and characterized by X-ray crystallography. The thiol and amine complexes react slowly with acetonitrile to give free thiol or amine and the acetonitrile complex. With the thiol complex, the reaction is dissociative. The thiolate complex has been oxidized to its Ru(III) radical cation and the solution EPR spectrum of that radical cation recorded. Cobaltocene reduces the thiol complex to the thiolate complex. The 1H and 31P NMR signals of the thiolate complex in acetonitrile become very broad whenever the thiolate and thiol complexes are present simultaneously. The line broadening is primarily due to electron exchange between the thiolate complex and its radical cation; the latter is generated by an unfavorable redox equilibrium between the thiol and thiolate complexes. Pyramidal inversion of sulfur in the thiol complex is fast at room temperature but slow at lower temperatures; major and minor conformers of the thiol complex were observed by 31P NMR at -98 degrees C in CD2Cl2.

Ruthenium complexes of diphenylphosphino derivatives of carboxylic amides: Synthesis and characterization of bidentate P,N- and P,O-chelate ligands and their reactivity towards [RuCl2(PPh3)3]

“…Whereas Norton et al [24] reported only one 31 P NMR signal (of PPh 3 , δ = −4 ppm) for a CDCl 3 solution of [RuCl 2 (PPh 3 ) 3 ], we observed a more complex 31 P NMR spectrum of a CDCl 3 solution of our product. In addition to the main signal at 41.0 ppm (which was very broad) we observed a signal of PPh 3 and two sets of dublets (both of them characteristic of cis-situated Rubound PPh 3 groups).…”

“…Following literature methods [24,25], which report the synthesis of [RuCl 2 (PPh 3 ) 3 ] from commercial RuCl 3 ⋅ 3H 2 O, we prepared [RuCl 2 (PPh 3 ) 3 ] from elemental Ruthenium without isolating the intermediate Ru(III)-chloride: A mixture of Ruthenium powder (0.750 g, 7.42 mmol), NaOH (4.00 g, 100 mmol) and NaClO 3 (2.63 g, 24.7 mmol) was cautiously heated in a crucible (using a Bunsen burner) for 15 min (until the evolution of gas from the deep red melt ceased). The mixture was allowed to cool to ambient temperature and was then dissolved in conc.…”

“…Following literature methods [24,25] mmol), NaOH (4.00 g, 100 mmol) and NaClO 3 (2.63 g, 24.7 mmol) was cautiously heated in a crucible (using a Bunsen burner) for 15 min (until the evolution of gas from the deep red melt ceased). The mixture was allowed to cool to ambient temperature and was then dissolved in conc.…”

Synthesis and Characterization of η6‐Arene Ruthenium Complexes Bearing Oxopentadienyl and Phosphine Ligands

“…A similar 31 P NMR spectroscopic behavior has been reported for compounds [{(η 6 ‐ p ‐cymene)RuClN 3 } 2 (μ 2 ‐dppe)] [ δ = 26.7 (d)],7a [{(η 6 ‐C 6 Me 6 )RuXN 3 } 2 (μ 2 ‐dppe)] [X = N 3 , δ = 31.1],7b [X = Cl, δ = 30.3],7b [(η 6 ‐C 6 H 6 )RuCl 2 ] 2 (μ 2 ‐dppe) [ δ = 23.3 (s)],7c [{CpRu(N 3 )} 2 (μ 2 ‐dppe) 2 ] [ δ = 39.19],8a [{CpRuCl} 2 (μ 2 ‐dppe) 2 ] [ δ = 37.10],8a and [{CpRu(SnCl 3 ) 2 } 2 (μ 2 ‐dppe)] [ δ = 43.5 (s)],8b as well as three intermediates species observed in the phosphine substitution reactions between CpRuCl(PPh 3 ) 2 and dppe: CpRuCl(PPh 3 )(κ 1 ‐dppe) [ δ = 41.51 (d), –12.10],8a CpRuCl(κ 1 ‐dppe) 2 [ δ = 40.72 (d), –12.31],8a and [{CpRuCl(PPh 3 )} 2 (μ 2 ‐dppe)] [ δ = 43.11 (d), 42.76 (d)] 8a. In agreement with the presence of a bridging dppe ligand in compound 5 , the 31 P NMR shows an upfield shift compared to complexes where the dppe is acting as a chelate in mononuclear ruthenium derivatives, such as: [(η 6 ‐C 6 H 6 )Ru(κ 2 ‐dppe)Cl]Cl [ δ = 70.4 (s)],7c CpRuCl(κ 2 ‐dppe) [ δ = 79.9],9 [CpRu(L)(κ 2 ‐dppe)]BPh 4 [ δ = 78.3–82.9],9 Cp*RuX(κ 2 ‐dppe) [X = Cl, δ = 73.5–74.6],10,11 [X = N 3 , δ = 75.7],11 [X = H, δ = 90.2],12 [Cp*RuX(κ 2 ‐dppe)]BF 4 [X = (H) 2 , δ = 71.3, (η 2 ‐H 2 ), δ = 77.4],12 and CpRu(κ 2 ‐dppe)SnCl 3 [ δ = 77.8 (s)],8b or dinuclear compounds where the bidentate dppe is also coordinated only to one metal atom, such as {Cp(PPh 3 ) 2 Ru}C≡C‐C≡C{Ru(κ 2 ‐dppe)Cp} δ = 86.1 and {Cp(κ 2 ‐dppe) 2 Ru}C≡C‐C≡C{Ru(κ 2 ‐dppe)Cp} δ = 86.7 ppm 13…”

Alkyl group-tagged ruthenium indenylidene complexes: Synthesis, characterization and metathesis activity

“…For drying dichloromethane, CaH 2 was used as drying agent whereas for toluene, n-hexane, n-pentane and 1,4-dioxane, sodium was employed as drying agent and benzophenone was used as indicator. The compounds RuCl 2 (PPh 3 ) 3 [34], 4-methyl-3-phenyl-1-pentyn-3-ol [23], 4,4-dimethyl-3-phenyl-1-pentyn-3-ol [24], 1-cyclohexyl-1-phenyl-2-propyn-1-ol [25] and (1-(allyloxy)prop-2-yne-1,1-diyl)dibenzene [35] were prepared according to the literature. n-Hexane, n-pentane, 1,4-dioxane and toluene were purchased from Fiers.…”