Kinetics and mechanism of oxidation of aromatic hydrocarbons by Ru(trpy)(bpy)O/sup 2 +/

Journal Article · Wed Sep 22 00:00:00 EDT 1982 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00383a013· OSTI ID:6011711

Thompson, M S; Meyer, T J

The kinetics of oxidation of p-/sup -/O/sub 2/CC/sub 6/H/sub 4/CH(CH/sub 3/)/sub 2/,p-/sup -/O/sub 2/CC/sub 6/H/sub 4/CH/sub 2/CH/sub 3/,and p-/sup -/O/sub 2/CC/sub 6/H/sub 4/CH/sub 3/ by Ru(trpy)(bpy)O/sup 2 +/ (trpy is 2,2',2''-terpyridine; bpy is 2,2'-bipyridine) to the corresponding ..cap alpha.. alcohols in water and of C/sub 6/H/sub 5/CH(CH/sub 3/)/sub 2/ and C/sub 6/H/sub 5/CH/sub 3/ by Ru(bpy)/sub 2/(py)O/sup 2 +/ in acetonitrile have been studied. The following conclusions are drawn from kinetics data obtained spectrophotometrically: (1) Rate constants increase with increasing alkyl substitution; for the carboxylates in water at 24.3/sup 0/C, k = 12.2 +/- 1.2, 3.4 +/- 0.3, and 0.43 +/- 0.04 M/sup -1/ s/sup -1/ in the order shown above. (2) Rate constants decrease dramatically for the reactions in acetonitrile; k(24.3/sup 0/C) = 0.026 +/- 0.003 M/sup -1/ s/sup -1/ for isopropylbenzene. (3) In water, rate constants are independent of added O/sub 2/ or of changes in ionic strength. (4) In acetonitrile the added nucleophiles water, tert-butyl alcohol, or bromide ion enter the rate law directly in terms first order in added nucleophile. From the temperature dependence of k for the oxidation of p-/sup -/O/sub 2/CC/sub 6/H/sub 4/CH(CH/sub 3/)/sub 2/, ..delta..H/sup + +/ = 7 +/- 1 kcal/mol and ..delta..S/sup + +/ = -32 +/- 4 eu. It is concluded that the redox step for the reactions involves a two-electron, hydride ion transfer step. The reactions occur by a template mechanism in that oxo group transfer from Ru to the substrate does not occur and the added oxygen atom must come from the solvent, p-/sup -/O/sub 2/CC/sub 6/H/sub 4/CH(CH/sub 3/)/sub 2/ (-H:/sup -/; +H/sub 2/O) ..-->.. p-/sup -/O/sub 2/CC/sub 6/H/sub 4/C(OH)(CH/sub 3/)/sub 2/. The solvent or added nucleophile (in acetonitrile) is directly involved in the redox step, apparently by assisting the loss of the hydride ion by electron pair donation.

• Research Organization: Univ. of North Carolina, Chapel Hill
• OSTI ID: 6011711
• Journal Information: J. Am. Chem. Soc.; (United States), Vol. 104:19
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
AROMATICS
OXIDATION
RUTHENIUM COMPLEXES
REDOX REACTIONS
BIPYRIDINES
CHEMICAL REACTION KINETICS
AZINES
CHEMICAL REACTIONS
COMPLEXES
HETEROCYCLIC COMPOUNDS
KINETICS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIDINES
REACTION KINETICS
TRANSITION ELEMENT COMPLEXES
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)