High Valent Oxo-molybdenum Complexes as Efficient Catalysts for C-X Bond Forming Reactions

Noronha, Rita G. de; Fernándes, Ana C.

doi:10.2174/138527212798993158

Cited by 29 publications

(14 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The growing interest in the coordination complexes of cisdioxo molybdenum(VI) is mainly due to their reactivity in various oxygen atom transfer reactions. [1][2][3][4][5] Besides, they have proven useful as biomimetic models for mononuclear molybdoenzymes. [6,7] As a result, many efforts have been put on synthesizing new cis-dioxomolybdenum(VI) complexes with a large variety of ligands, [8À 11] among which bi-, tri-and multidentate Schiff bases are especially attractive for the following reasons: easy preparation, tunable electronic and steric characteristics by varying the substituents on the amine or on the carbonyl or on both.…”

Section: Introductionmentioning

confidence: 99%

Cis‐Dioxo‐molybdenum(VI) Complexes with Diaminoguanidinium and Triaminoguanidinium Schiff Bases and Their Catalytic Application for Epoxidation of Cyclohexene

Jia

Zhou

et al. 2020

ChemistrySelect

View full text Add to dashboard Cite

Diaminoguanidinium and triaminoguanidinium Schiff bases of 1,3-bis(3,5-di-tert-butyl-2-hydroxyphenylmethylideneamino) guanidine hydrochloride (H 5 saldag tBu2 ⋅ HCl) and tris(3,5-di-tertbutyl-2-hydroxybenzylidene)-triaminoguanidinium chloride (H 5 saltag tBu2 ⋅ HCl) are synthesized. Treatment of H 5 saldag tBu2 ⋅ HCl with Na 2 MoO 4 ⋅ 2H 2 O or (NH 4) 6 Mo 7 O 24 ⋅ 4H 2 O under different molar ratios afforded mono-and di-nuclear molybdenum(VI) complexes of [(MoO 2)(MeOH)(H 3 saldag tBu2)] (1), [(MoO 2) 2 (MeOH) 2 (Hsaldag tBu2)] ⋅ 2DMF (2 ⋅ 2DMF), and [(MoO 2) 2 (Hsaldag tBu2)] ⋅-[(MoO 2) 2 (H 2 O) 2 (Hsaldag tBu2)] (3). Interactions of H 5 saltag tBu2 ⋅ HCl with Na 2 MoO 4 ⋅ 2H 2 O or (NH 4) 6 Mo 7 O 24 ⋅ 4H 2 O under different reaction conditions resulted mono-, di-, and tetra-nuclear molybdenum(VI) complexes of [(MoO 2)(MeOH)(H 3 saltag tBu2)] (4), [(MoO 2)(H 2 O)(H 3 saltag tBu2)] (5), [(MoO 2) 2 (H 2 O)(DMF)(Hsaltag tBu2)] ⋅ 3DMF (6) (Ref [31]), and [(MoO 2) 4 (DMF) 2 (Hsaltag tBu2) 2 ] ⋅ 2H 2 O (7 ⋅ 2H 2 O). Complexes 1-7 were characterized by IR, 1 H NMR and UV/vis spectroscopies. Molecular structures of H 5 saltag tBu2 ⋅ MeOH, 1, 2 ⋅ 2DMF, 3-5 and 7 ⋅ 2H 2 O are confirmed by single crystal X-ray diffraction ananlysis, which shows that the diaminoguanidinium and triaminoguanidinium Schiff bases are coordinated to the cis-{MoO 2 } 2 + moieties via ONN atoms to form five-and sixmembered rings, sharing one MoÀ N bond. The catalytic properties of these cis-dioxo-molybdenum(VI) complexes for epoxidation of cyclohexene were also investigated.

show abstract

Section: Introductionmentioning

confidence: 99%

Cis‐Dioxo‐molybdenum(VI) Complexes with Diaminoguanidinium and Triaminoguanidinium Schiff Bases and Their Catalytic Application for Epoxidation of Cyclohexene

Jia

Zhou

et al. 2020

ChemistrySelect

View full text Add to dashboard Cite

show abstract

“…This reactivity has been further exploited in a 'diagonal' approach to CO 2 reduction/ functionalisation, for example in the use of CO 2 as the C1 source for amine N-methylation. 3,37,[44][45][46][47][48][49][50][51][52][53][54] High oxidation state transition metal oxo complexes 55 have been studied in CO 2 reduction chemistry and have been shown to react to form metal carbonates where, in the case of molybdate, the resulting carbonate undergoes hydrosilylation to formate and silylated molybdate, albeit stoichiometrically. [56][57][58][59] Furthermore, rheniumĲV) mono and dioxo complexes act as catalysts for the hydrosilylation of organic carbonyls, [60][61][62][63][64][65] but this activity is not generally seen for the parent perrhenate, ReO 4…”

Section: Introductionmentioning

confidence: 99%

Reduction of carbon dioxide and organic carbonyls by hydrosilanes catalysed by the perrhenate anion

Morris

Weetman

Wennmacher

et al. 2017

Catal. Sci. Technol.

View full text Add to dashboard Cite

aThe simple perrhenate salt [NĲhexyl) 4 ]ĳ(ReO 4 )] acts as a catalyst for the reduction of organic carbonyls and carbon dioxide by primary and secondary hydrosilanes. In the case of CO 2 , this results in the formation of methanol equivalents via silylformate and silylacetal intermediates. Furthermore, the addition of alkylamines to the reaction mixture favours catalytic amine N-methylation over methanol production under certain conditions. DFT analysis of the mechanism of CO 2 reduction shows that the perrhenate anion activates the silylhydride forming a hypervalent silicate transition state such that the CO 2 can directly cleave a Si-H bond. IntroductionThe hydrosilylation of CO 2 to silylformates and silylethers is an attractive route for CO 2 utilisation as, unlike hydrogenation, this reaction is exergonic due to the comparative ease of Si-H bond activation and the strength of the Si-O bond, and the availability of relatively inexpensive and environmentally benign hydrosilanes. 66 Important to this chemistry is the formation of a lipophilic ion pair in which electrostatic and hydrogen-bonding interactions are enhanced in the hydrophobic phase. This catalyst has the advantages of ease of synthesis and manipulation and lack of air-sensitivity, and the recovery of the precious metal is driven by straightforward reverse phase-transfer. Given the efficacy of this new catalyst system and the use of high oxidation state rhenium oxo complexes in reduction catalysis, it is shown here that perrhenate can act as a catalyst for the reduction of carbon dioxide to methanol equivalents by hydrosilanes, that the methylation of alkylamines using CO 2 as the C 1 source occurs under similar catalytic conditions, and that this method can be used to reduce aldehydes and ketones to silylalcohols. Results and discussion Reduction of carbon dioxideInitially, the reaction between CO 2 (2.5 bar), PhSiH 3 (2.0 mmol), and pyridinium perrhenate 1 (2.0 mol%) at 80°C in C 6 D 6 in a Teflon-tapped NMR tube was monitored by 1 H NMR spectroscopy. However, only 15% consumption of hydrosilane is seen under these conditions after 16 h ( Fig. S2 and S3, ESI †). In contrast, when the reaction is carried out using the simple lipophilic quaternary ammonium salt [NĲhexyl) 4 ]ĳReO 4 ] 2 (2.5 mol%) with PhSiH 3 in C 6 D 6 at 1 bar of

show abstract

“…High-valent oxidomolybdenum(VI) complexes have proven to be excellent molecular catalysts for a plethora of organic transformations, including oxidations, C-X bond-forming reactions, reductions, and deoxygenations. [1][2][3][4][5][6][7] Complexes that have attracted particular attention include [MoO 2 (acac) 2 The systematic investigation of ligand effects has allowed the rational design of ligands to prepare more efficient homogeneous catalysts. [8][9][10][11] Aromatic bidentate nitrogen ligands (N-N), such as 2,2′-bipyridine derivatives and pyrazolylpyridines, are excellent options, since they are resistant to oxidative degradation and afford complexes of the type [MoO 2 X 2 (N-N)] and [MoO(O 2 ) 2 (N-N)] with high coordinative stability.…”

Section: Introductionmentioning

confidence: 99%

Chemistry and Catalytic Performance of Pyridyl‐Benzimidazole Oxidomolybdenum(VI) Compounds in (Bio)Olefin Epoxidation

et al. 2017

View full text Add to dashboard Cite

The chemistry and catalytic performance of the dichlorido complex [MoO2Cl2(pbim)] (1) [pbim = 2‐(2‐pyridyl)‐benzimidazole] in the epoxidation of olefins is reported. Complex 1 acts as a precatalyst and is more effective with tert‐butylhydroperoxide (TBHP) as the oxidant than with aq. hydrogen peroxide: the cis‐cyclooctene (Cy) reaction with TBHP gave 98 % epoxide yield at 70 °C/24 h. Catalyst characterization showed that 1 is transformed in situ to the oxidodiperoxido complex [MoO(O2)2(pbim)] (2), with H2O2 and a hybrid molybdenum(VI) oxide solid formulated as [MoO3(pbim)] (3) with TBHP. The hybrid material 3 was prepared on a larger scale and explored for the epoxidation of the biorenewable olefins methyl oleate, methyl linoleate, and (R)‐(+)‐limonene. With TBHP as the oxidant, 3 acts as a source of soluble active species of the type 2. A practical method for recycling oxidodiperoxidomolybdenum(VI) catalysts for the Cy/TBHP reaction is demonstrated by using an ionic liquid as the solvent for the molecular catalyst 2.

show abstract

High Valent Oxo-molybdenum Complexes as Efficient Catalysts for C-X Bond Forming Reactions

Abstract: The purpose of this review is to demonstrate that high valent oxo-molybdenum complexes are excellent catalysts for C-X bond forming reactions, including carbon-carbon, carbon-heteroatom (C-N, C-O, C-S, C-P, C-Br, and C-I), and carbon-hydrogen bonds.

Cited by 29 publications

References 49 publications

Cis‐Dioxo‐molybdenum(VI) Complexes with Diaminoguanidinium and Triaminoguanidinium Schiff Bases and Their Catalytic Application for Epoxidation of Cyclohexene

Cis‐Dioxo‐molybdenum(VI) Complexes with Diaminoguanidinium and Triaminoguanidinium Schiff Bases and Their Catalytic Application for Epoxidation of Cyclohexene

Reduction of carbon dioxide and organic carbonyls by hydrosilanes catalysed by the perrhenate anion

Chemistry and Catalytic Performance of Pyridyl‐Benzimidazole Oxidomolybdenum(VI) Compounds in (Bio)Olefin Epoxidation

Contact Info

Product

Resources

About