β-Diketones: Coordination and Application

Crossman, Aaron S.; Marshak, Michael P.

doi:10.1016/b978-0-08-102688-5.00069-6

Cited by 8 publications

(6 citation statements)

References 656 publications

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“…The biological effects of these compounds are of great interest [6][7][8][9], and they have also been investigated as potential antiviral agents [10,11]. Although β-diketones represent one of the oldest classes of chelating ligands [12][13][14][15], their coordination chemistry continues to attract much interest, due to the ability of related metal complexes to support several unique and important catalytic reactions [16][17][18][19][20][21][22]. In this regard, it is often noted that even modestly sterically hindered β-diketones offer improvements over the parent acetylacetone [23].…”

Section: Introductionmentioning

confidence: 99%

“…β-diketones are known to form complexes with almost every metal [16] and despite the enormous amount of work devoted to the synthesis and characterization of copper(II) β-diketonate complexes [27], there are relatively few reports devoted to the corresponding Cu(I) complexes showing undergoing disproportionation to copper metal and copper(II) compounds in the absence of stabilizing ligands [28][29][30]. In particular, very little attention has been paid to the study of triorganophosphane adducts of copper(I) β-diketonates of the general formula (β-diketonate)Cu(PR 3 ) n , although a rich structural diversity can also be expected there [31][32][33][34][35][36][37][38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

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New Copper Complexes with N,O-Donor Ligands Based on Pyrazole Moieties Supported by 3-Substituted Acetylacetone Scaffolds

Del Gobbo,

Santini,

Dolmella

et al. 2024

Molecules

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The new 3-monosubstituted acetylacetone ligands, 3-(phenyl(1H-pyrazol-1-yl)methyl)pentane-2,4-dione (HLacPz) and 3-((3,5-dimethyl-1H-pyrazol-1-yl)(phenyl)methyl)pentane-2,4-dione (HLacPzMe), were synthesized and used as supporting ligands for new copper(II) and copper(I) phosphane complexes of the general formulae [Cu(HLacX)2(LacX)2] and [Cu(PPh3)2(HLacX)]PF6 (X = Pz (pyrazole) or PzMe (3,5-dimethylpyrazole)), respectively. In the syntheses of the Cu(I) complexes, the triphenylphosphine coligand (PPh3) was used to stabilize copper in the +1 oxidation state, avoiding oxidation to Cu(II). All compounds were characterized by CHN analysis, 1H-NMR, 13C-NMR, FT-IR spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). The ligands HLacPz (1) and HLacPzMe (2) and the copper complex [Cu(PPh3)2(HLacPz)]PF6 (3) were also characterized by X-ray crystallography. The reactivity of these new compounds was investigated and the new compounds 4-phenyl-4-(1H-pyrazol-1-yl)butan-2-one (7) and 4-(3,5-dimethyl-1H-pyrazol-1-yl)-4-phenylbutan-2-one (8) were obtained in basic conditions via the retro-Claisen reaction of related 3-monosubstituted acetylacetone, providing efficient access to synthetically useful ketone compounds. Compound 8 was also characterized by X-ray crystallography.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New Copper Complexes with N,O-Donor Ligands Based on Pyrazole Moieties Supported by 3-Substituted Acetylacetone Scaffolds

Del Gobbo,

Santini,

Dolmella

et al. 2024

Molecules

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“…As chelating ligands, 1,3-diketonates have found a broad range of applications in homogeneous catalysis with transition metals. [24] Therefore, we applied palladium(II) acetylacetonate [Pd(acac) 2 ] [25] as catalyst for the twofold oxidative cyclization of 5 b. However, after a reaction time of 1 h a mixture of starting material 5 b, monocyclized product 6 b, and 1,1'-bicarbazole 7 b was obtained along with large amounts of decomposition (entry 10).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of 1,1′‐Bicarbazoles by Sequential Iron(III)‐ and Palladium(II)‐Catalyzed Oxidative Coupling Reactions**

Thoran,

Puls,

Knölker

2024

Chemistry A European J

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The iron(III)‐catalyzed oxidative coupling of diarylamines to 2,2ʹ‐bis(arylamino)‐1,1ʹ‐biaryls and subsequent twofold palladium(II)‐catalyzed oxidative cyclization provide a convergent synthetic route to 1,1ʹ‐bicarbazoles. Screening a range of different palladium(II) salts led to palladium(II) acetate, pivalate, and hexafluoroacetylacetonate as the most efficient catalysts. Remarkably, the twofold palladium(II)‐catalyzed oxidative cyclization can also be performed under argon. The mechanism for the oxidative cyclization under an inert gas presumably involves regeneration of the catalytically active palladium(II) species by oxidative addition of pivalic acid.

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“…When calculating the electron eager monodentate TPP−Co(II) acac 1 + , it was no surprise that it showed a significantly increased binding energy of −2.87 eV toward TPP (Figure 8b). In real solutions, such a transient state of a charged complex could be short-lived before binding with the negatively charged residual of the protonating agent, 104 be it a −OH from the epoxy backbone or impurities in the resin. In an extreme consideration, water was split and a free OH − (which has the highest possible polarity in the system) coordinates to the positively charged TPP−Co(II) acac 1 + , forming TPP−(OH)Co(II) acac 1 .…”

Section: A Reversed Tpp Reactivity Evolution Was Observed Inmentioning

confidence: 99%

Controlled Triphenylphosphine Reactivity for Epoxy Resin Cure by Transition-Metal β-Diketonates

Liu

Sun

et al. 2022

Chem. Mater.

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Cure kinetics control of epoxy resins is critical for the realization of many structures and processes and is often manipulated by catalyst design. We here show an example of switchable Lewis base catalytic activity through ligand-controlled metal coordination. Divalent first-row transition-metal (Co, Ni, Cu, Zn) β-diketonates with methyl or trifluoromethyl end groups have found distinguished thermal latent curing behaviors in triphenylphosphine (TPP)-catalyzed epoxy resins, namely, a deceleration pattern for metal acetylacetonates (acac2) and an inhibition pattern for metal hexafluoroacetylacetonates (6Facac2). Comparative analysis exposed the major initiation mechanism as phosphine attack on epoxide rings, where the phosphine reactivity was regulated by metal coordination whose strength depends on the original diketone ligands. TPP further stabilized the metal chelates and suppressed their dissociation. Feed ratio studies of Co(II) chelates revealed an equilibrium built upon TPP, metal chelate, and the formed passivated complex through numerical analysis. Further, temperature dependence of the equilibrium constants suggested a reversed metal-base affinity evolution of the two chelates during heating, which determines the equivalent TPP concentration. Chemical and thermal characterizations on the formed complexation states identified structural changes during high-temperature treatment and, along with density functional theory (DFT) calculation, verified the Co–P binding energy that marks the TPP “effectiveness” in each stage to catalyze epoxy cure. It was found that the competition between incoming phosphine and original diketone ligands, depending on the basicity of the latter, dictates the initial relative affinity between metal and phosphine, while beyond phosphine ligand stabilization, the diketone ligand dynamics at elevated temperatures were accompanied by the respective Co–P affinity change. Across different metals, the deviation from the “natural order” in metal-phosphine affinity can also be qualitatively understood from the ligand competition concept, where the same ligand effects on the field stabilization schemes are expected as the distinctions caused by ligand fluorination were consistent throughout d7–d10 metal cations. The knowledge gained from this work could benefit future design of thermal latent catalysts and shed light on the capability of Lewis base reactivity control through adjusting transition-metal coordination spheres.

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β-Diketones: Coordination and Application

Cited by 8 publications

References 656 publications

New Copper Complexes with N,O-Donor Ligands Based on Pyrazole Moieties Supported by 3-Substituted Acetylacetone Scaffolds

New Copper Complexes with N,O-Donor Ligands Based on Pyrazole Moieties Supported by 3-Substituted Acetylacetone Scaffolds

Synthesis of 1,1′‐Bicarbazoles by Sequential Iron(III)‐ and Palladium(II)‐Catalyzed Oxidative Coupling Reactions**

Controlled Triphenylphosphine Reactivity for Epoxy Resin Cure by Transition-Metal β-Diketonates

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