32580-85-1Relevant academic research and scientific papers
Mechanistic Dichotomy in Proton-Coupled Electron-Transfer Reactions of Phenols with a Copper Superoxide Complex
Bailey, Wilson D.,Dhar, Debanjan,Cramblitt, Anna C.,Tolman, William B.
supporting information, p. 5470 - 5480 (2019/05/29)
The kinetics and mechanism(s) of the reactions of [K(Krypt)][LCuO2] (Krypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, L = a bis(arylcarboxamido)pyridine ligand) with 2,2,6,6-tetramethylpiperdine-N-hydroxide (TEMPOH) and the para-substituted phenols XArOH (X = para substituent NO2, CF3, Cl, H, Me, tBu, OMe, or NMe2) at low temperatures were studied. The reaction with TEMPOH occurs rapidly (k = 35.4 ± 0.3 M-1 s-1) by second-order kinetics to yield TEMPOa€￠ and [LCuOOH]a on the basis of electron paramagnetic resonance spectroscopy, the production of H2O2 upon treatment with protic acid, and independent preparation from reaction of [NBu4][LCuOH] with H2O2 (Keq = 0.022 ± 0.007 for the reverse reaction). The reactions with XArOH also follow second-order kinetics, and analysis of the variation of the k values as a function of phenol properties (Hammett σ parameter, O-H bond dissociation free energy, pKa, E1/2) revealed a change in mechanism across the series, from proton transfer/electron transfer for X = NO2, CF3, Cl to concerted-proton/electron transfer (or hydrogen-atom transfer) for X = OMe, NMe2 (data for X = H, Me, tBu are intermediate between the extremes). Thermodynamic analysis and comparisons to previous results for LCuOH, a different copper-oxygen intermediate with the same supporting ligand, and literature for other [CuO2]+ complexes reveal significant differences in proton-coupled electron-transfer mechanisms that have implications for understanding oxidation catalysis by copper-containing enzymes and abiological catalysts.
Synthesis, Structure, and Reactivity of Zerovalent Group 6 Metal Pentacarbonyl Aryl Oxide Complexes. Reactions with Carbon Dioxide
Darensbourg, Donald J.,Sanchez, Kathryn M.,Reibenspies, Joseph H.,Rheingold, Arnold L.
, p. 7094 - 7103 (2007/10/02)
The synthesis of (M=Cr, Mo, W; R=Ph, C6H4CH3-m) from the reaction of M(CO)5THF and in tetrahydrofuran is reported.In the absence of a carbon monoxide atmosphere these mononuclear species readily aggregate via a CO dissociation pathway to the tetranuclear species 44.It was possible to isolate pure crystalline samples of the derivatives by precipitation from solutions under a carbon monoxide atmophere.The complex was characterized in the solid-state by X-ray crystallography. crystallizes in the space group with cell dimensions a=9.416(3) Angstroem, b=12.665(2) Angstroem, c=18.371(3) Angstroem, α=92.38(1) deg, β=94.50(2) deg, γ=95.85(2) deg, V=2168.3 Angstroem3, Z=4, and RF=7.71percent.An additional salt of the tungsten phenoxide complex has been crystallized that contains 0.5 equiv of water, i.e., .This species has as well been characterized by X-ray crystallography. crystallizes in the space group P21/c with cell dimensions a=17.545(5), b=25.322(8), c=10.337(3), β=102.52(3) deg, V=4483(2) Angstroem3, Z=8, and RF=5.60percent.The water molecule is shown to be hydrogen bonded between ligated -OPh ligands of adjacent W(CO)5OPh(1-) anions.This intermolecular hydrogen-bonding interaction is observed in tetrahydrofuran solution as well between alcohols and W(CO)5OPh(1-).The M(CO)5OR(1-) (M=Cr, W) derivatives were demonstrated to undergo facile insertion reactions with CO2, COS, and CS2 to afford the corresponding metal pentacarbonyl phenyl carbonate, phenyl thiocarbonate, and phenyl dithiocarbonate complexes.This carbon dioxide insertion reaction isreversible, and the rate of insertion is unaffected by carbon monoxide pressures up to 10 atm.The relative rates of insertion of CO2, COS, and CS2 into the M(CO)5OPh(1-) anions are Cr > W and CS2 > COS > CO2.On the other hand, in the presence of ligands at the metal center that are sterically more demanding than CO, i.e., cis-M(CO)4(L)OPh(1-) derivatives, the relative rates of carbon dioxide insertion are W > Cr and L=P(OMe)3 > PMe3 > PPh3.The W(CO)5XC(X)OPh(1-) (X=O or S) derivatives underwent hydrolysis in the presence of small quantities of water to provide the corresponding W(CO)4(CX2O)(2-) products.One of these products, namely, 2, was subjected to an X-ray crystallographic investigation.The salt crystallizes in the space group with cell dimensions a=10.513(5) Angstroem, b=15.881(10) Angstroem, c=8.130(6) Angstroem, α=101.69(6) deg, β=92.12(5) deg, γ=83.25(5) deg, V=1319.8 Angstroem3, Z=2, and RF=3.01percent.The W-O bond distances (2.204 Angstroem) are quite similar to those observed (2.203 Angstroem) in the W-OPh(1-) complexes.The carbonate ligand is bidentate with a very acute O-W-O angles of 59.4 deg.
MoFe3S4(S-p-C6H4Cl)4(3,6-(C3H5)2C6H2O2).
Mascharak,Armstrong,Mizobe,Holm
, p. 475 - 483 (2007/10/02)
Reaction of the solvated cubane-type clusters left bracket MFe//3S//4(SR)//3((C//3H//5)//2cat)(MeCN) right bracket **2** minus (M equals Mo, W; R equals Et, p-C//6H//4Cl; (C//3H//5)//2cat equals 3,6-diallycatecholate) with the ligands L equals p-ClC//6H//
