Alcohols ROH Research Articles

Rhodium complexes with planar-chiral cyclopentadienyl ligands: synthesis from tert-butylacetylene and catalytic performance in C-H activation of arylhydroxamates.

The rhodium complex [(C5H2tBu2CH2tBu)RhCl2]2 with an asymmetric cyclopentadienyl ligand was prepared in 95% yield by the reaction of [(cod)RhCl]2 with tert-butylacetylene in the presence of AlCl3. A similar reaction in the presence of InBr3 gave the cationic fulvene complex [(C5H2tBu2 = CHtBu)Rh(cod)]InBr4 (70%), which can add alcohols ROH and produce more bulky catalysts [(C5H2tBu2CH(OR)tBu)RhCl2]2. The enantiomers of these planar-chiral complexes were separated by thin-layer chromatography in the presence of L-phenylglycinol. The complexes catalyze the reactions of arylhydroxamates with alkenes giving dihydroisoquinolones in excellent yields (80-90%), but with moderate enantioselectivity (typically 20-50% ee).

Toward a 1,4-Diphosphinine-Based Molecular CPS-Ternary Compound.

Synthesis of the tricyclic 1,3-dithiole-2-thione-derived 1,4-dihydro-1,4-diphosphinine is presented using a base-induced ring formation protocol and chloro(diethylamino)(1,3-dithiole-2-thion-4-yl)phosphane as the starting point. P-oxidation reactions of dihydrodiphosphinine by chalcogens led to bis(P-oxide), bis(P-sulfide), or bis(P-selenide), respectively; all tricyclic compounds were obtained as cis/trans mixtures. 1,4-Dihydro-1,4-diphosphinine was converted into 1,4-dichloro-1,4-dihydro-1,4-diphosphinine. This compound is almost insoluble in organic solvents, furnished selectively the trans-bis(amino) derivative upon a 2-fold P-substitution reaction with the weak nucleophile potassium bis(trimethylsilyl)amide, and reacted also with alcohols ROH (R = nBu, iPr, tBu) to give cis/trans mixtures of the corresponding bis(alkoxy) derivatives. Furthermore, the dichloro derivative could be reduced to a 1,4-diphosphinine using PnBu3, but, unfortunately, the stubbornly insoluble product could be neither purified nor crystallized. Despite this, we achieved a thermal [4 + 2] cycloaddition reaction of this first CPS-ternary compound with diethylacetylene dicarboxylate to obtain the corresponding diphosphabarrelene, thus providing indirect evidence for the aromatic tricyclic diphosphinine. Detailed density functional theory studies on the formation of 1,4-diphosphinine provided insights into formation pathways as well as NMR, IR, and UV/vis data.

Features of the Identification of Trialkyl Phosphites in Reaction Mixtures and Their Characterization by Gas Chromatography–Mass Spectrometry

The interaction of aliphatic alcohols ROH with phosphorus trichloride in the absence of bases leads to the formation of exclusively dialkyl phosphonates (RO)2PHO. To obtain trialkyl phosphites (RO)3P, insufficiently described to date, the pH of the reaction mixtures was adjusted by adding N,N-dimethylaniline (pKa 5.1 ± 0.1). The identification of trialkyl phosphites directly in reaction mixtures without preparative isolation implies a joint consideration of their mass spectra and gas chromatographic retention indices, provided that all other components of such mixtures are identified. The need to comply with this condition has led to the identification of several homologues of a previously uncharacterized series of 2-alkoxy-1,3,2-dioxaphospholanes, formed from a random admixture of ethylene glycol. The use of such combined mass spectrometric parameters as homologous increments of retention indices helps to distinguish trialkyl phosphites from isobaric dialkyl phosphonates; the compounds of both series belong to the homologous group of y = 12, y ≡ M(mod14). Despite the absence of molecular ion signals in the electron ionization (EI) mass spectra, the molecular weights of trialkyl phosphites can be estimated. In addition, a comparison of the homologous increments of retention indices shows that, compared with dialkyl phosphonates, trialkyl phosphites are significantly less polar.

A Sustainable Process for the Production of Varnishes Based on Pelargonic Acid Esters

AbstractThis work demonstrates the possibility of using pelargonic acid (PA) esters as solvents for vegetable‐based varnishes. First, PA was efficiently produced through a chemocatalytic cleavage of oleic acid, practicing an optimized scale‐up of previously developed conditions. PA was then esterified with several alcohols ROH (R = Me, i‐Pr, n‐Bu, n‐Hex, 2‐ethylhexyl, and sec‐octyl) and the products were formulated with a commercial rosin (Phenolic Modified Rosin Esters). Dynamic light scattering (DLS) measures and determination of rheological parameters of the corresponding varnishes disclosed their suitability for applications in offset, coldset, heatset printing inks, and coatings. Furthermore, inks obtained were used to efficiently produce preliminary industrial offset prints.

Nickel Pincer Complexes with Frequent Aliphatic Alkoxo Ligands [(iPrPCP)Ni-OR] (R = Et, nBu, iPr, 2-hydroxyethyl). An Assessment of the Hydrolytic Stability of Nickel and Palladium Alkoxides.

A series of nickel pincer complexes with terminal alkoxo ligands [(iPrPCP)Ni-OR] (R = Et, nBu, iPr, CH2CH2OH; iPrPCP is the 2,6-bis(diisopropylphosphinomethyl)phenyl pincer ligand) was synthesized and fully characterized. Together with the previously reported methoxo analogues of Ni and Pd, these complexes constitute a unique series of isostructural late transition-metal alkoxides. Spectroscopic and X-ray diffraction data provide direct indications of the strong polarization of their covalent Ni-OR bonds. One of the most salient features of this class of compounds is their facile hydrolysis with traces of moisture, leading to equilibrium mixtures with the corresponding hydroxides [(iPrPCP)M-OH] (M = Ni or Pd) and alcohols, ROH. To compare the hydrolytic stability of nickel and palladium alkoxides, we performed NMR titrations of both hydroxides with several alcohols and determined the corresponding equilibrium constants. In general, these constants are ca. 1 order of magnitude smaller for M = Ni than Pd, indicating that Ni alkoxide complexes are more readily hydrolyzed than their Pd counterparts. For alkoxide complexes containing heteroatom-free R groups, the tendency to hydrolyze decreases as the parent alcohol ROH becomes more acidic, that is, R = Me > Et > iPr. This intuitive trend is broken for 2-methoxyethanol, the most acidic alcohol investigated. The hydroxo/2-methoxyethanol exchange equilibrium constants are comparable to those of ethanol (M = Ni) or methanol (M = Pd), showing that the corresponding 2-methoxyethoxide complexes are more prone to hydrolysis than anticipated. These experimental observations were rationalized in the light of density functional theory calculations.

Mild N‐Alkylation of Amines with Alcohols Catalyzed by the Acetate Ru(OAc)2(CO)(DiPPF) Complex

The acetate complex Ru(OAc)2 (DiPPF) (2) obtained from Ru(OAc)2 (PPh3 )2 (1) and 1,1'-bis(diisopropylphosphino)ferrocene (DiPPF) reacts cleanly with formaldehyde affording Ru(OAc)2 (CO)(DiPPF) (3) in high yield. The monocarbonyl complex 3 (0.4-2 mol %) efficiently catalyzes the N-alkylation of primary and secondary alkyl and aromatic amines using primary alcohols ROH (R=Et, nPr, nBu, PhCH2 ) under mild reaction conditions (30-100 °C) with an alcohol/amine molar ratio of 10-100. Formation of the monohydride RuH(OAc)(CO)(DiPPF) (4) has been observed by reaction of 3 with iPrOH in the presence of NEt3 at RT through an equilibrium reaction.

Study of the controlled temperature reaction between closo-decahydrodecaborate and alcohols in H2SO4 medium

The reactions of the ammonium salt of closo-decahydrodecaborate (NH4)2B10H10 with alcohols were studied in concentrated sulfuric acid medium. Alcohols ROH (R = CH3 ,C 2H5 ,C 3H7, iso-C3H7 ,C 4H9, 2-C4H9, ter-C4H9, C5H11) played the role of solvent and ligand, simultaneously. These Electrophile Induced Nucleophilic Substitution Reactions were conducted at two different temperatures (25 ◦ C or reflux) in atmospheric air and produced (2-B10H9OR) 2− , (2,7(8)-B10H8(OR)2) 2- and/or (B10H7(OR)3) 2- . The rate of the reaction and the nature of the product formed depended on the temperature, on the alcohol, and on the reaction duration. The reactions at 25 ◦ C, if proceeded, produced mainly the monoalkoxy derivative, (2-B10H9OR) 2- . For the longer chain alcohols (4 carbons and above) the increase in the reaction duration and the temperature resulted in higher substitution, thus producing the dialkoxy (2,7(8)-B10H8(OR)2) 2- and trialkoxy (B10H7(OR)3) 2- derivatives. Meanwhile only the monoalkoxy (2-B10H9OR) 2- plus the dialkyloxonium (2-B10H9OR2) − derivatives were produced with the shorter alcohols (1 to 3 carbons) at refluxing temperature. All these derivatives were isolated in their pure forms on DEAE-cellulose column with adequate yields, and characterized by 11 B, 13 C, 1 H NMR, negative ESI and TLC.

Co(II)-mediated synthesis of 2-carbamimidoylbenzoates and isoindole-1,3-diaminates

Phthalonitrile, acetoxime and cobalt(II) nitrate hexahydrate are combined in acetone with formation of stable and easy to handle Co(II) complex [Co{C6H4C(NH2)NC(ONCMe2)2}2](NO3)2 (1). Interaction of 1 with excess alcohols ROH (also used as solvents) and 2 equiv of (NH4)2S leads, in one-step, to alkyl 2-carbamimidoylbenzoate nitrates [C6H4COOR{2-C(NH2)2}]NO3 [R=CH3, C2H5, C3H7, CH(CH3)2]. Similarly, N1,N3-dialkyl-1H-isoindole-1,3-diaminate nitrates [C6H4C(NR′)NC(NR′)]NO3 [R=C3H7, C4H9, C(CH3)3, CH2CH2OH, CH2CH2SC2H5) can be directly produced from 1 by its reaction with 4 equiv of amines and 2 equiv of (NH4)2S in alcoholic media.

Rhenabenzenes and Unexpected Coupling Products from the Reactions of Rhenacyclobutadienes with Ethoxyethyne

Treatment of Na[Re(CO)5] with methyl 3-(naphthalen-1-yl)propiolate (NpC≡CCO2Me) followed by acetyl chloride and alcohols ROH (R = Me, nPr) afforded the rhenacyclobutadiene complexes Re{-C(Np)═C(CO2Me)C(OR)═}(CO)4. Reactions of these rhenacyclobutadiene complexes with HC≡COEt produced the rhenabenzene complexes Re{-C(Np)═C(CO2Me)C(OR)═CHC(OEt)═}(CO)4 and new rhenacyclobutadienes with a pendant vinyl substituent Re{-C(Np)═C(C(OR)═CH(CO2Et))C(OMe)═}(CO)4. In the vinyl-substituted rhenacyclobutadiene products, the ethyl of the ester group is from the alkyne HC≡COEt, the alkyl of the ReC(OR) group is from the ester group of the starting rhenacyclobutadienes, and the alkyl group of the OR of the vinyl substituent is from the ReC(OR) group of the starting rhenacyclobutadienes. A plausible mechanism for the formation of the vinyl-substituted rhenacyclobutadienes is discussed.

Alcoholysis of fluoroform

Abstract Fluoroform (CHF 3 ) reacts with alkali metal alkoxides MOR (M = Na, K) in the corresponding alcohols ROH (R = Me, Et, i -Pr, t -Bu, and Allyl) at 80–120 °C to give orthoformate esters HC(OR) 3 in 55–90% yield. Particularly notable is the formation of HC(OBu- t ) 3 in 75–80% yield (62% isolated yield; X-ray), an exotic organic compound that has been previously synthesized only once (3% yield). Solutions of NaOH in ROH (R = Me, Et, i -Pr and t -Bu) react with CHF 3 to give NaF, HCOONa, and orthoformates HC(OR) 3 . Hydrolysis of fluoroform with MOH (M = Na, K) at 140 °C produces largely MF and HCOOM along with small quantities of CO.

Formation of diazohydroxides ArN2OH in aqueous acid solution: polarographic determination of the equilibrium constant KR for the reaction of 4‐substituted arenediazonium ions with H2O

In aqueous acid (pH <4) solutions, in the dark, and in the absence of reductants, arenediazonium ions, ArN2+ decompose spontaneously through the rate‐limiting formation of the extremely unstable aryl cation that reacts with any nucleophile present in its solvation shell (DN + AN mechanism). However, in weak acidic and alkaline solutions, ArN2+ react with H2O and OH− at the terminal nitrogen to give azo adducts of the type ArN2OH that are in equilibrium with the parent ArN2+. The diazohydroxide, in this case an acid, is in equilibrium with its conjugate base, and diazoate ArN2O−. The equilibrium constant for reaction with OH− has been determined for a limited number of ArN2+ from kinetic measurements but not with H2O (KR). Here, we have exploited the electrochemical properties of ArN2+ to determine, for the first time, the equilibrium constants KR of formation of 4‐substituted X–ArN2OH (XH, Me, MeO, Br, and NO2), which can decompose in several ways including Z–E isomerization or further reaction with OH− to give diazoate ArN2O−. The technique applied was differential pulse polarography, which is very selective and sensitive. The determined pKR values are 5–6, and they are somewhat higher than those obtained for the reaction of ArN2+ with alcohols ROH (pKDE = 3–5) under similar acidic conditions. The KR values are not very sensitive to changes in the nature of the substituent in the aromatic ring and a linear Hammett plot with a slope of ρ = 0.58 was obtained. Copyright © 2013 John Wiley & Sons, Ltd.

Novel Gold(I) and Silver(I) Complexes of Phosphorus-1,1,-dithiolates and Molecular Structure of [O,O'-(Bornyl)2PS2]H3NC(CH3)3.

BackgroundThe novel chiral phosphorus-1,1-dithiolates [4-CH3OC6H4P(S)(OR)S]-[H3NC(CH3)3]+ were synthesized by the reaction of [RPS2)]2 (R = 4-MeOC6H4) or P2S5 and the respective alcohol ROH (R = myrtanyl, 2-naphthylethyl, myrtenyl, borneol) in toluene. The reaction of phosphorus-1,1-dithiolates 1–4 and Au(tht)Cl, AuClPPh3 or AgNO3 and PPh3 gave rise to gold(I)- and silver(I)-complexes in THF. All compounds have been characterised by elemental analyses, IR, NMR (1H-, 13C- and 31P-) spectroscopy as well as MS measurements. Optical rotation values confirmed the chirality of the compounds. The Compound 4 has been characterized structurally by X-ray crystallography.ResultsPhosphorus-1,1,-dithiolate compounds were formed as liquids and were treated with suitable amine in order to convert them to their salts 1–4 . They have been successfully characterized spectroscopically (IR, 1H, 13C, 31P NMR) as well as mass spectra. The compound 4 has been also structurally by X-ray crystallography. The compound 4 crystallizes in the orthorhombic space group P2(1)2(1)2(1) with Z = 4. Compounds containing phosphorus and sulfur donor atoms are excellent ligands due to offering many metal complexes especially group 11–12 metals. The synthesis of gold(I) and silver(I) complexes with chiral phosphorus-1,1,-dithiolate and triphenylphosphine have been described and investigated.ConclusionsIn the present work, we report the synthesis, charactreization of the chiral phosphorus-1,1-dithiolate ligands and preparing the gold(I) and silver(I) phosphorus-1,1-dithiolate or S-donor with phosphine complexes. The molecular structure of the Compound 4 was determined by X-ray diffraction. Due to an easy synthesis method of phosphorus-1,1-dithiolate compounds and a good complexion reagent, it is possible the improvement of the collecting metallic gold or silver from the minerals. When the more ionic salt of phosphorus-1,1-dithiolate compounds were prepared in this way, the water can be used as a cheap solvent. As a result, it can be an alternatively method for the collecting metallic gold or silver from the minerals in future.

1.3.4. Transesterification reaction of 2-methoxycarbonylethyldichlorotin hydroxide

The title compound, CH3OCOCH2CH2SnCl2(OH) (1), readily undergotransesterification into the corresponding analogues, ROCOCH2CH2SnCl2(OH) (R = CH3CH2, 2; CH3CH2CH2, 3; CH2=CHCH2,4), when reacted with an alcohol ROH under reflux. The structural featuresof these compounds have been described, and the possible mechanismof the transesterification reaction has been suggested.

Solubility of monohydric aliphatic alcohols in water and aqueous HCl solutions

The mutual solubility of components in the extraction system HCl-monohydric aliphatic alcohol ROH (R = C5–C10)-H2O at 20°C was studied.

Chemistry of magnesium alkyls supported by 1,5,9-trimesityldipyrromethene and 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene. A comparative study

The compounds LMgBun(THF) and L′MgBun(THF) where L = 1,5,9-trimesityldipyrromethene and L′ = 2-[(2,6-diisopropylphenyl)amino]-4-[(2,6-diisopropylphenyl)imino]pent-2-ene have been prepared from reactions between MgBun2 and the protonated ligands LH and L′H, respectively. Single crystal X-ray crystallographic studies reveal that in each compound the Mg2+ ion is in a distorted tetrahedral environment and further that the ligand L is more sterically demanding with respect to access to the Mg–Bun group. Related alkyl complexes (R = Me, Et, Prn, Pri, n-hexyl and CH2CH2Ph) were prepared from reactions involving LLi(THF) or L′Li(THF) and the appropriate RMgX (X = Cl or Br) and characterized by 1H NMR spectroscopy. Those where R = CH2CH2X (X = alkyl or phenyl) have characteristic α-CH2 proton resonances which are the part of an AA′XX′ pattern. Reactions with alcohols ROH (1 equiv.) give the kinetic products LMg(OR)(THF) and L′Mg(OR)(THF) which are isolable and kinetically persistent when R = a bulky group such as But and the structure of LMg(OBut)(THF) is reported and compared with that of the known compound L′Mg(OBut)(THF). With less bulky groups the compounds are labile toward ligand scrambling and the compound L′MgBun(THF) reacts with alcohols (2 equiv.) to give L′H and Mg(OR)2. Reactions with amines and carbon dioxide are described which indicate the greater reactivity of the Mg–Bun group relative to both the L′ and L ligand. With PhCHO, Ph2CO and cyclohexanone both LMgBun(THF) and L′MgBun(THF) react via β-hydrogen atom transfer to generate the appropriate alkoxide with the elimination of 1-butene. Similarly L-lactide reacts by β-H transfer to give poly-L-lactide (P-L-LA) and 1-butene while rac-lactide yields atactic polylactide in toluene–dichloromethane solutions but in the presence of ≥10 equiv. of THF, heterotactic PLA is formed. The ring-opening polymerization of e-caprolactone also is initiated by β-H transfer and is about ten times faster than for lactide; kp(LA) = 10.7 M−1 s−1vs. kp(CL) = 110 M−1 s−1. Interestingly, the presence of lactide completely suppresses the polymerization of e-caprolactone.

Protonolysis of [(iPrO)TiMo5O18]3−: access to a family of TiMo5Lindqvist type polyoxometalates

The tetra-n-butylammonium (TBA) salts of [((i)PrO)TiMo(5)O(18)](3-) 1 and [((i)BuO)TiMo(5)O(18)](3-) 2 were prepared by hydrolysis of mixtures of (TBA)(2)[Mo(2)O(7)], (TBA)(4)α-[Mo(8)O(26)] and Ti(OR)(4) (R = (i)Pr or (i)Bu) in acetonitrile. Treatment of (TBA)(3)1 with alcohols ROH afforded primary and tertiary alkoxide derivatives [(RO)TiMo(5)O(18)](3-) (R = Me 3, (t)Bu 4), whilst aryloxides [(ArO)TiMo(5)O(18)](3-) were prepared by reacting 1 with phenols ArOH (Ar = C(6)H(4)Me-4 5, and C(6)H(4)CHO-2 6). Oxo-bridged [(μ-O)(TiMo(5)O(18))(2)](6-)7 rather than the hydroxo derivative [(HO)TiMo(5)O(18)](3-) was obtained upon hydrolysis of 1. X-Ray crystal structures of TBA salts of anions 3-7 show that titanium is six-coordinate in all cases, although titanium sites are disordered over two trans positions in 3. Mo-O bond length alternation is observed in the Mo(4)O(4) planes of 4 and 7 and in one of the two independent anions in the structure of 3. In solution, (17)O NMR spectra are consistent with the higher anionic charge compared to [Mo(6)O(19)](2-) and reveal an order of basicity for the anions [LM'Mo(5)O(18)](3-) associated with the ability of {LM'}(3+) to donate/withdraw electron density from {Mo(5)O(18)}(6-). Protonolysis reactions of 1 and 3 were slower than for tungstate analogues and the possibility of initial protonation at TiOM (M = Mo) rather than TiOR (M = W) in a proton-assisted S(N)1 mechanism for ligand exchange in [(RO)TiM(5)O(18)](3-) is discussed.

Facile O–H Bond Activation in Alcohols by [Cp*RuCl(iPr2PSX)] (X = Pyridyl, Quinolyl): a Route to Ruthenium(IV) Hydrido(alkoxo) Derivatives

The complexes [Cp*RuCl((i)Pr(2)PSX)] (X = pyridyl, quinolyl) react directly with alcohols ROH (R = Me, Et, (i)Pr, (n)Pr) and NaBPh(4), affording the novel cationic hydrido(alkoxo) derivatives [Cp*RuH(OR)((i)Pr(2)PSX)][BPh(4)]. These ruthenium(IV) compounds result from the formal oxidative addition of the alcohol to the 16-electron fragment {[Cp*Ru((i)Pr(2)PSX)](+)}, generated in situ upon chloride dissociation. The hydrido(alkoxo) complexes are reversibly deprotonated by a strong base such as KOBu(t), yielding the neutral alkoxides [Cp*Ru(OR)((i)Pr(2)PSX)], which are remarkably stable toward β elimination and do not generate the corresponding hydrides. The hydrido(alkoxo) complexes undergo a slow electron-transfer process, releasing H(2) and generating the dinuclear ruthenium(III) complex [{Cp*Ru(κ(2)-N,S-μ S-SC(5)H(4)N)}(2)][BPh(4)](2). In this species, the Ru-Ru separation is very short and consistent with what is expected for a Ru≡Ru triple bond.

Synthesis and Structural Characterization of a New Molecular Precursor for BaHfO3: A Simple Approach to Eu-Based Phosphors

A single-source molecular precursor [Ba4Hf2(μ6-O)(μ3,η2-OR)8(μ-OR)2(μ-ROH)4Cl4] (ROH = CH3OCH2CH2OH) for mixed-metal oxide materials was prepared via elimination of the cyclopentadienyl ring from Cp2HfCl2 as CpH, in the presence of Ba(OR)2 in an alcohol ROH as a source of protons. The precursor was characterized by elemental analysis, infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy, and single-crystal X-ray structural analysis. This complex undergoes thermal decomposition at 800 °C to a BaCl2/BaHfO3 mixture. After barium dichloride has been leached from the raw powder using deionized water, the resulting particles are of submicrometer size (30–50 nm). Preliminary studies of barium hafnate doped with Eu3+ sintered at 900 °C showed that a dominant luminescence band belongs to the strong electric dipole transition 5D0→7F2.

Chiral Heterobimetallic Gold(I) Ferrocenyldithiophosphonato Complexes

AbstractChiral and non‐chiral ferrocenyldithiophosphonates [tBuNH3][Fe(η5‐C5H5){η5‐C5H4P(OR)S2}] were prepared from [Fe(η5‐C5H5){η5‐C5H4PS(μ‐S)}]2 and the respective alcohol ROH [R = bornyl (1), myrtenyl (2), adamantyl (3)] and tBuNH2 as base. The reaction with [AuCl(tht)] (tht = tetrahydrothiophene) gave the corresponding chiral (1a, 2a) and non‐chiral (3a) heterobimetallic dimeric gold(I) ferrocenyldithiophosphonato complexes [Au{Fe(η5‐C5H5)(η5‐C5H4P(OR)(μ‐S)2)}]2 [R = bornyl (1a), myrtenyl (2a), adamantyl (3a)]. Compounds 1–3 and 1a–3a were characterised spectroscopically (IR, 1H, 13C, 31P NMR) and by mass spectrometry, and the chiral heterobimetallic dimeric gold(I) ferrocenyldithiophosphonato complex 1a was also structurally characterised by X‐ray crystallography.

Chemoselective Sulfide and Sulfoxide Oxidations by CpMo(CO)3Cl/HOOR: a DFT Mechanistic Study

The mechanism of sulfide and sulfoxide oxidation with peroxides (ROOH, R = H, Me), catalyzed by Mo(VI) complexes, was investigated by means of DFT/PBE1PBE calculations. Two different catalytic systems were considered: the first is based on the dioxocyclopentadienyl (Cp) complex CpMoO2Cl (Cp = η5-C5H5), also active as a catalyst for olefin epoxidation, and the second based on MoO2Cl2. The most favorable mechanism in the Cp system is initiated by the O−H activation of the HOOR oxidant, which in the presence of CpMoO2Cl leads to formation of CpMoO(OH)(OOR)Cl. Although this is the active species for olefin epoxidation, an alternative pathway with lower energy is available. With the crucial H-bond assistance of another oxidant molecule, the oxoperoxo complex CpMoO(O2)Cl forms, with release of alcohol ROH as byproduct and a calculated energy barrier below 25 kcal mol−1. The mechanisms unveiled for sulfide to sulfoxide oxidation and for sulfoxide to sulfone oxidation are equivalent in their general features and ...