14333-24-5Relevant articles and documents
Fragmentation pathways of [Re2(μ-OR)3(CO)6]- (R = H, Me) and ligand exchange reactions with oxygen donor ligands, investigated by electrospray mass spectrometry
Jiang, Chenghua,Andy Hor,Van Kai, Yaw,Henderson, William,McCaffrey, Louise J.
, p. 3197 - 3203 (2000)
The rhenium hydroxy and methoxy carbonyl complexes [Re2(u-OR)3(CO)6] (R = H or Me) have been studied by negative-ion electrospray mass spectrometry (ESMS). The complexes undergo facile exchange reactions with protic compounds, including alcohols and phenols. With dimethyl malonate, ester hydrolysis occurs giving carboxylatecontaining complexes, and with H2O2 or Bu'OOH, oxidation to ReO4- occurs. The feasibility and extent of these reactions can conveniently, rapidly, and unambiguously be determined by electrospray mass spectrometry, and is dependent on the acidity and steric bulk of the protic compound. The results also suggest that the complexes can be used as versatile starting materials for the synthesis of a wide range of analogous [Re2(μ-OR)3(CO)6]- complexes by simple reaction with an excess of the appropriate alcohol. By varying the applied cone voltage the fragmentation pathways have been investigated; the hydroxy complex undergoes dehydration followed by CO loss, whereas for the methoxy complex -hydride elimination (and CO loss) is observed, with confirmation provided by deuterium labelling studies. Under ESMS conditions, the neutral complexes [Re2(μ-OR)2(μ-dppf)(CO)6] [R = H or Me; dppf= 1,1'-bis(diphenylphosphino)ferrocene] undergo substantial solvolysis and hydrolysis to give mainly mononuclear species; simple parent ions (e.g. [M + H]+) are not formed in appreciable abundance, probably due to the lack of an efficient ionisation pathway. The Royal Society of Chemistry 2000.
Mechanistic Studies on the cis-(1+) and (3-) Oxidations of the ReIV2 Complex (4-)
Atkinson, J. William,Hong, Mao-Chun,House, Donald A.,Kyritsis, Panayotis,Li, Yu-Jin,et al.
, p. 3317 - 3322 (1995)
Rate constants (25 deg C) have been determined for the oxidation of the Re(IV)2 complex di-μ-oxobis, (4-), I = 1.00 M (ClO4(1-) or Cl(1-)).Whereas the complex is itself stable in air at pH 7 over many days, at lower pH there is a slow decay of the 446 nm peak (ε = 6840 M-1cm-1 per Re(IV)2) to give in air the colourless perrhenate(VII) (1-) product, peak at 225 nm (ε = 3400 M-1cm-1).The kinetics indicate a protonation step, equilibrium constant K = 2.4 M-1, followed by the decay proces k = 4.3E-5 s-1.With the one-equivalent oxidants cis-(1+) (1.0 V) and (3-) (0.80 V) , stoichiometries of 6 mol of oxidant per Re(IV4)2 are obtained indicating conversion through to Re(VII).Two kinetic stages have been monitored with the oxidant in large excess.For the raction with V(V) as oxidant the first stage is dependent on and as well as , giving the rate constant k1 = 3.31E4 M-2s-1.Since in the corresponding reaction with Mo(V) as oxidant the reaction is independent of (kMo = 2.27E4 M-1s-1), it is concluded that the V(V) reactant introduces the -dependent term.The second stage of the V(V) reaction gives the rate law dependence k2obs = k2+k0, but with the less strong Mo oxidant k2obs = k0 wchich is ca. 0.20 s-1.The spectrum of the Re(IV)Re(V) intermediate, peak at 529 nm (ε = 3800 M-1cm-1), was obtained by stopped-flow rapid-scan spectrophotometry.Reactions of less than full stoichiometric amounts of V(V) with Re(IV)2, followed by QAE-Sephadex chromatography at 0 deg C gave orange-pink (peak at ca. 495 nm) and maroon (ca. 550 nm) intermediates, which undergo spontaneous decay.
Essays ueber Metallorganische Chemie V. Stand und Aussichten der Rhenium-Chemie in der Katalyse
Herrmann, Wolfgang A.
, p. 1 - 18 (1990)
The most recent review article on catalytic epoxidation reactions gives a rather discouraging statement of the heavier group VII transition metal compounds as oxidation catalysts : The catalytic activity of technetium seems to be comparable to that of rhenium ..., and both seem to be low .The present account briefly describes the status of rhenium chemistry in catalysis, showing that there are many more perspectives than were first believed.It is shown that high-valent organorhenium oxides function as very effective catalysts in both olefin metathesis (heterogeneous catalysis) and in olefin oxidation (homogeneous catalysis).In this context it becomes evident that rhenium chemistry in general has been much less investigated and understood than that of the neighbouring elements tungsten and osmium.Furthermore, work concerning technetium compounds is necessary in order to gain better insight in catalytic and other properties of the corresponding rhenium compounds.Beyond the known, relationship between technetium and rhenium with regard to their inorganic and coordination compounds, the first similarities in the chemistry of their organic compounds are being uncovered, at the same time marked differences cannot be neglected.
Burgess, John,Fawcett, John,Peacock, Raymond D.,Pickering, David
, (1976)
Parker, David,Roy, Partha S.
, p. 251 - 254 (1988)
The photooxidation of hexabromorhenate(IV) in ethanol
Estill, Christina N.,Cohen, Jessica L.,Hoggard, Patrick E.
, p. 688 - 689 (2008)
Irradiation (λ a secondary photochemical reaction. Copyright Taylor & Francis Group, LLC.
Ligand exchange reactions of Re2(u-OR)3(CO)6r (R = H, Me) with sulfur, selenium, phosphorus and nitrogen donor ligands, investigated by electrospray mass spectrometry
Jiang, Chenghua,Andy Hor,Van Kai, Yaw,Henderson, William,McCaffreyc, Louise J.
, p. 3204 - 3211 (2000)
Negative-ion electrospray mass spectrometry has been used to investigate the reactions of the dinuclear rhenium aggregates [Re2(u-OH)3(CO)6]- 1 and [Re2(u-OMe)3(CO)6]- 2 with a range of thiols, benzeneselenol, and some other sulfur-, phosphorus- and nitrogen-based ligands. Typically up to three of the hydroxo ligands are replaced by simple thiolates, giving the series of species [Re2(OH)2(SR)(CO)6]-, [Re2(OH)(SR)2(CO)6]-, and [Re2(SR)3(CO)J-. Similarly, reaction of 1 with H2S gives the species [Re2(u-SH)3(CO)6]-, which undergoes an analogous fragmentation process to [Re2(u-OH)3(CO)6r, at high cone voltages, by loss of H2S and formation of [Re2(S)(SH)(CO)6]-. With ligands which are good chelating agents (such as dithiocarbamates R2NCS2-, and thiosalicylic acid, HSC6H4CO2H) initial substitution of one or two OH groups readily occurs, but on standing the dimer is cleaved giving [Re(S2CNR2)2-(CO)3]- and [Re(SC6H4CO2)(CO)3]-. The different reactivities of the dithiol reagents benzene-1,2- and benzene-1,4-dimethanethiol towards 1 are also described. Complex 1 also reacts with aniline, and with primary (but not secondary) amides RC(O)NH2, giving monosubstituted species [Re2(OH)2(NHPh)(CO)6]- and [Re2(OH)2{NHC(O)R}-(CO)6]- respectively. The reactions with adenine and thymine, and with the inorganic anions thiocyanate and thiosulfate, are also described. The Royal Society of Chemistry 2000.
Redox-active ligands facilitate bimetallic O2 homolysis at five-coordinate oxorhenium(V) centers
Lippert, Cameron A.,Amstein, Stephen A.,David Sherrill,Soper, Jake D.
, p. 3879 - 3892 (2010)
Five-coordinate oxorhenium(V) anions with redox-active catecholate and amidophenolate ligands are shown to effect clean bimetallic cleavage of O 2 to give dioxorhenium(VII) products. A structural homologue with redox-inert oxalate ligands does not react with O2. Redox-active ligands lower the kinetic barrier to bimetallic O2 homolysis at five-coordinate oxorhenium(V) by facilitating formation and stabilization of intermediate O2 adducts. O2 activation occurs by two sequential Re-O bond forming reactions, which generate mononuclear n 1-superoxo species, and then binuclear trans-μ-1,2-peroxo-bridged complexes. Formation of both Re-O bonds requires trapping of a triplet radical dioxygen species by a cis-[Rev(O)(cat)2]anion. In each reaction the dioxygen fragment is reduced by 1e, so generation of each new Re-O bond requires that an oxometal fragment is oxidized by 1e. Complexes containing a redox-active ligand access a lower energy reaction pathway for the 1e- Re-O bond forming reaction because the metal fragment can be oxidized without a change in formal rhenium oxidation state. It is also likely that redox-active ligands facilitate O2 homolysis by lowering the barrier to the formally spin-forbidden reactions of triplet dioxygen with the closed shell oxorhenium(V) anions. By orthogonalizing 1e and 2e redox at oxorhenium(V), the redox-active ligand allows high-valent rhenium to utilize a mechanism for O 2 activation that is atypical of oxorhenium(V) but more typical for oxygenase enzymes and models based on 3d transition metal ions: O2 cleavage occurs by a net 2e process through a series of 1e steps. The implications for design of new multielectron catalysts for oxygenase-type O 2 activation, as well as the microscopic reverse reaction, O-O bond formation from coupling of two M=O fragments for catalytic water oxidation, are discussed.
A novel series of rhenium-bipyrimidine complexes: Synthesis, crystal structure and electrochemical properties
Chiozzone, Raul,Gonzalez, Ricardo,Kremer, Carlos,Cerda, Maria Fernanda,Armentano, Donatella,De Munno, Giovanni,Martinez-Lillo, Jose,Faus, Juan
, p. 653 - 660 (2008/02/08)
Four novel rhenium complexes of formula [ReCl4(bpym)] (1), [ReBr4(bpym)] (2) PPh4[ReCl4(bpym)] (3) and NBu4[ReBr4(bpym)] (4) (bpym = 2,2′-bipyrimidine, PPh4 = tetraphenylphosphon
