Kinetics and Mechanism of Phosphine Autoxidation Catalyzed by Imidorhenium(V) Complexes

Wei-dong, Wang; Espenson, James H.

doi:10.1021/ic000940k

“…The structural formulas of selected high-valent oxorhenium compounds 1 − 6 are given in Chart . − Compound 1 catalyzes oxygen atom transfer between two closed-shell molecules, as in YO + X → Y + XO. In that sense, the rhenium complexes can be discussed together with enzymes and enzyme mimics for biological oxygen atom transfer containing Mo − or W. − One example of a reaction catalyzed by 1 is that between pyridine N -oxide and triphenylphosphane. , The sequence of reactions in eqs 1−2 describes the chemistry…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of Oxygen Atom Abstraction from a Dioxo-Rhenium(VII) Complex

Dixon

¹

,

Espenson

²

2002

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The kinetics of reaction between triarylphosphanes and two newly prepared dioxorhenium(VII) compounds has been evaluated. The compounds are MeRe(VII)(O)(2)("O,S") in which "O,S" represents an alkoxo, thiolato chelating ligand. With MeReO(3), ligands derived from 1-mercaptoethanol and 1-mercapto-2-propanol form MeRe(O)(2)(met), 2, and MeRe(O)(2)(m2p), 3. These compounds persist in chloroform solution for several hours at room temperature and for 2-3 weeks at -22 degrees C, particularly when water is carefully excluded. They were obtained as red oils with clean (1)H NMR spectra, but attempts to obtain pure, crystalline products were not successful because one decomposition pathway shows a kinetic order >1. The fastest reaction occurs between P(p-MeOC(6)H(4))(3) and 2; k(298) = 215(7) L mol(-1) s(-1) in chloroform at 25(1) degrees C. The other rate constants follow a Hammett correlation against 3sigma, with rho = -0.69(7). This study relates to oxygen atom transfer reactions catalyzed by MeReO(mtp)PPh(3), 1, in which MeRe(O)(2)(mtp), 4, is a postulated intermediate that does not build up to a measurable concentration during the catalytic cycle. Compound 2 does not react with MeSTol, but MeS(O)Tol was formed when tert-butyl hydroperoxide was added. This suggests that equilibrium lies to the left in this reaction, 2 + MeSTol + L = MeReO(met)L + MeS(O)Tol, and is drawn to the right by a reaction between MeReO(met)L and the hydroperoxide. Triphenyl arsane does not react with 2, but thermodynamic versus kinetic barriers were not resolved.

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“…267 The Re() complex MeRe(NAr) 2 (PY 3 ) 2 (Ar = 2.6-diisopropylphenyl; Y = PR n -Ph 3 Ϫ n , P(OR) n Ph 3 Ϫ n , R = Me, Et) catalyses the oxidation of a range of phosphines by O 2 yielding the corresponding phosphine oxide. 268 Kinetic study of the catalysis suggests that the mechanism for these reactions involves the η 2 -peroxo species MeRe(NAr) 2 -(η 2 -O 2 ).…”

Section: Redox Reactionsmentioning

confidence: 99%

27 Mechanisms of reactions in solution

Davies¹

2002

Annu. Rep. Prog. Chem., Sect. A: Inorg. Chem.

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Rhenium: Organometallic Chemistry

Romão

¹

2005

Encyclopedia of Inorganic Chemistry

2

0

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The organometallic chemistry of Rhenium spans 11 oxidation states. Since many ligands stabilize several oxidation states, this chemistry is described by ligand type. Re‐Re multiple bonded organometallic complexes, Polynuclear organometallic complexes, and Bioorganometallic Chemistry, uncoverable in this fashion, are treated separately. The CO ligand dominates the chemistry of the lower oxidation states (Re −III to Re II ) most of which is derived from Re 2 (CO) 10 and the consequences of the rupture of its Re‐Re bond. [Re(CO) 5 ] • , [Re(CO) 5 ] − and Re(CO) 5 X are the most important products of Re‐Re homolysis, reduction and oxidation, respectively, and originate a vast chemistry. [ReX x (CO) y L z ] is the largest family of organorhenium complexes. The luminescent fac ‐[ReX(CO) 3 L 2 ] molecules assume high practical relevance in photoresponsive materials and sensors. Polyhydrides [ReH x L y ] lose H 2 upon thermal, photochemical or oxidative activation promoting alkane dehydrogenation. The abundant [Re(CO) x H y ] clusters are important building blocs for catalysts and materials. [ReH(CO) 4 ] n are analogues of cycloalkanes. Mononuclear homoleptic alkyls and aryls of Re in high oxidation states are limited to ReMe 6 and [Re(2‐MeC 6 H 4 ) 4 ]. Instead, carbenes and carbynes, as the remarkable [Re(≡CCMe 3 )(=CHCMe 3 )(CH 2 CMe 3 ) 2 ], are common. Re VII oxo and imido complexes also originate carbene/carbyne complexes active in olefin metathesis catalysis. ReO 3 Me (MTO) is a uniquely versatile catalyst in a wide variety of oxidation and O transfer catalysis. ReO 2 Me derivatives are active catalysts namely in aldehyde olefination. η 2 ‐, η 3 ‐, η 4 ‐ (dienes), η 6 ‐ (arenes) and η 7 ‐ (cycloheptatrienyl) ligands play a limited role in the organorhenium chemistry. Exceptional is, however, the activation of η 2 ‐arenes by Re I complexes. The dearomatized benzene ring in TpRe(CO)(MeIm)(η 2 ‐C 6 H 6 ) reacts as a diene. Unusual alkyne complexes appear in Re III and Re V oxides, e.g. ReR(O)(η 2 ‐RCCR) (R = H, alkyl). [Cp'Re(CO) 2 (η 3 ‐propargyl)] + complexes reveal a fascinating series of structural transformations and rearrangements. The cyclopentadienyl ligand (η 5 ‐C 5 R 5 = Cp’) shapes the large families of complexes of the fragments Cp’ 2 Re (rhenocene) Cp'Re(CO) 2 , [Cp'Re(NO)(PPh 3 )] + and Cp'ReO x X y . Hydrocarbyl transformations at these fragments and the understanding of the stereochemical control in enantioselective transformations of ligands bound to the chiral‐at‐metal fragment [Cp'Re(NO)(PPh 3 )] + are of outstanding relevance. Isoelectronic neutral or negative 6 e donors may enhance these transformations and support new ones. [Cp*Re(CO) 2 ] 2 and [Re(≡CCMe 3 )(OCMe 3 ) 2 ] 2 are rare examples of unsupported dimers of 16e fragments. Re isocyanide and nitrosyl complexes follow most of the structural and chemical patterns found for the carbonyl ligand. However, recent findings revealed that the participation of the O atom of the NO ligand in H bonding may lead to unexpected reactivity. Polynuclear Re complexes span a bewildering variety of synthetic methods and structural motifs. The ultimate rationale for their study is cooperative catalysis, as modelled in alkene hydrogenation with a Re/Pt binuclear complex and applied in petroleum refining with Pt x Re y clusters. Bioorganometallic chemistry is rapidly evolving into practical medical applications in diagnostics and therapy. Stable Re(CO) 3 fragments decorated with biologically active molecules are able to target Re compounds to specific tissues/organs. New synthetic methods have been developed for the synthesis of the required molecules in aqueous solution, avoiding the use of CO gas and classical high pressure synthesis.

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Kinetics and Mechanism of Phosphine Autoxidation Catalyzed by Imidorhenium(V) Complexes

Cited by 7 publications

References 28 publications

Kinetics and Mechanism of Oxygen Atom Abstraction from a Dioxo-Rhenium(VII) Complex

Kinetics and Mechanism of Oxygen Atom Abstraction from a Dioxo-Rhenium(VII) Complex

27 Mechanisms of reactions in solution

Rhenium: Organometallic Chemistry

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