Equilibria and kinetics of the reactions between hydrogen peroxide and methyltrioxorhenium in aqueous perchloric acid solutions

• Published in: Inorganic chemistry Vol. 32; no. 22; pp. 4683 - 4687
• Main Authors: Yamazaki, Shigekazu, Espenson, James H, Huston, Patrick
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.10.1993
• Subjects: 400201 - Chemical & Physicochemical Properties; CHALCOGENIDES; CHEMICAL REACTION KINETICS; COMPLEXES; EQUILIBRIUM; HYDROGEN COMPOUNDS; HYDROGEN PEROXIDE; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; KINETICS; MOLECULAR STRUCTURE; ORGANIC COMPOUNDS; ORGANOMETALLIC COMPOUNDS; OXIDES; OXYGEN COMPOUNDS; PEROXIDES; PH VALUE; REACTION KINETICS; REFRACTORY METAL COMPOUNDS; RHENIUM COMPLEXES; RHENIUM COMPOUNDS; RHENIUM OXIDES; TRANSITION ELEMENT COMPLEXES; TRANSITION ELEMENT COMPOUNDS
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic00074a007

In aqueous solutions the colorless compounds CH[sub 3]ReO[sub 3] (=MTO) and H[sub 2]O[sub 2] form 1:1 and 1:2 adducts. The latter is yellow, with [epsilon][sub 360] = 1.1 x 10[sup 3] L mol[sup [minus]1] cm[sup [minus]1]. Peroxide binding to MTO shows cooperativity, as shown by the inversion of the usual order of binding constants. The stepwise equilibrium constants are K[sub 1] = 7.7 L mol[sup [minus]1] and K[sub 2] = 145 L mol[sup [minus]1] at 25[degrees]C. The buildup of product, which occurs on the stopped-flow time scale at 9-680 mM H[sub 2]O[sub 2], is fit by biexponential kinetics. The equilibria and rates are independent of [H[sub 3]O[sup +]] in the range 10[sup [minus]1]-10[sup [minus]3] M. The peroxide complexes decompose more rapidly at lower [H[sub 3]O[sup +]], particularly at pH > 3. Possible structures for 1:1 and 1:2 MOT-H[sub 2]O[sub 2] adducts are presented and discussed.