A Tetraphosphane Imine Ligand Which Enforces Square‐Pyramidal Coordination

Zimmermann, Christopher; Heinemann, Frank W.; Grohmann, Andreas

doi:10.1002/ejic.200500281

Cited by 15 publications

(17 citation statements)

References 16 publications

(27 reference statements)

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“…The coordination pattern of L 2 thus generally echoes the observations made previously with metal complexes of related ligands of tetrapodal topology . More specifically, it closely mimics the coordination chemistry of copper(II) complexes of such ligands ,,. EPR spectra obtained both from powder samples and frozen methanol solutions of [ L 2 CuCl]Cl at T= 150 K, are in agreement with this structure (Figures S9 and 10 in the Supporting Information).…”

Section: Resultssupporting

confidence: 82%

Oxygen Delivery as a Limiting Factor in Modelling Dicopper(II) Oxidase Reactivity

Gülzow

Hörner

Strauch

et al. 2017

Chemistry A European J

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What is the most significant result of this study? Attempts to mimic metalloenzymes teach us about catalysis, and the lessons learnt find widespread application in an umber of chemical disciplines, including process engineering. Our catechol oxidase models show an unprecedented dependence of their reactivity on the method of oxygen administration:w hen going beyond the limits of homogeneously distributed reactants, by administering surplus dioxygen periodically during catalytic turnover, we observed reactivities increasing by factors of five to ten, in comparison with the well-established conditions of dioxygen saturation. This observation is not limited to our new system. Reference experiments with systems taken from the literature suggest that the effect, which is of interest in the context of reactive bubbly flows, is general, but has hitherto gone unnoticed. What was the inspiration for this cover design? When we were invited to submit ad esign, we took inspiration from the fact that the browning of cut fruit is effected by copper-and oxygen-dependent oxygenases, leading to melanine pigments, which are polymeric ortho-quinone derivatives. An abstract rendering of our dinuclear copper(II) complexes is shown in the foreground at left. In our cover art, as till life by Gabriele Endres, the browning of the half-eaten apple in the foreground denotes the enhanced reaction of our model substrate, ac atechol, under oxygen-enriched conditions, as provided by ab ubbly flow of oxygen. What other topics are you working on at the moment? We are interested in the activation of dioxygen and its exploitation as an environmentally benign, or green, oxidant, using bioinspired transition-metal complexes of tailor-made ligands. Our "workhorse" metal ions are iron and copper,i nt heir various oxidation states, and we are currently making our first forays into the coordination chemistry of manganese. Our ligands are polypodal, including tetra-and pentadentate ligands, as in the present work, or extended -tripodal hexadentate, as in recent spin-state dynamics studies. The former chelators shield am ajor part of the metal-coordination sphere, focusing the reactivity on one or two "labile" coordination sites. The coordinative strain of all these claw-like ligands can also be varied, enabling investigations, in which distortions of the coordination sphere and their influence on complex reactivity and spin multiplicity,c an be studied in isolation (and with reference to the concept of the entatic state). Invited for the cover of this issue is the group of Gerald Hçrner and Andreas Grohmann at the Technical University of Berlin. The image depicts that the browning of cut fruit is effected by copper-and oxygen-dependent oxygenases, leading to mela-nine pigments, which are polymeric ortho-quinone derivatives.R ead the full text of the article at

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Section: Resultssupporting

confidence: 82%

Oxygen Delivery as a Limiting Factor in Modelling Dicopper(II) Oxidase Reactivity

Gülzow

Hörner

Strauch

et al. 2017

Chemistry A European J

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“…In both cases, and within minutes, the reaction mixture deposited a blue precipitate, which was collected and recrystallized from methanol to obtain single crystals of 5 suitable for an X-ray structure determination ( Figure 3). [13] [Cu II 6 (4) 2 (μ-CF 3 The copper(II) ion in 5 is coordinated in a tetragonalpyramidal fashion, with five Cu1-N bonds of similar lengths [ Table 1; average: 2.064(3) Å].…”

Section: [Cu II (3)](clo 4 ) 2 (5)mentioning

confidence: 99%

Copper Complexes of “Superpodal” Amine Ligands and Reactivity Studies towards Dioxygen

et al. 2012

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The results of studies focussed on copper complexes of a variety of ligands with an NN4 donor set are reported. The permethylated tetrapodal ligand 2 forms a complex with copper(I) which, upon reaction with dioxygen at –90 °C, yields a product having a bis(μ‐oxido)dicopper(III) core (“O‐type” product, 10), as inferred from UV/Vis and resonance‐Raman spectroscopic data. The UV/Vis spectrum of 10 has two bands at 300 and 404 nm, with extinction coefficients of 9400 and 10400 L mol–1 cm–1, respectively. Resonance‐Raman spectra display two 16O/18O‐sensitive bands which, based on the isotopic shifts and the absolute frequencies, are attributed to the Cu–O stretching modes of the O‐type product. Complex 10 shows tyrosinase‐like activity, as its reaction with sodium p‐tert‐butylphenolate at –90 °C in THF yields p‐tert‐butylcatechol, in an ortho‐hydroxylation reaction (yield: 30 %). Two new rigid tetrapodal pentadentate ligands (the “superpods” 3 and 4) can be synthesized by condensation of the primary polyamine 1 with paraformaldehyde. Their copper(II) complexes (5 and 6) have been spectroscopically characterized. As ascertained by X‐ray crystallography, 5 has the CuII ion in a tetragonal‐pyramidal environment, with almost uniform Cu–N bond lengths (basal bonds: 2.052 Å and 2.070 Å; apical bond: 2.077 Å). No significant Jahn–Teller distortion is observed here. In 6, the ligand acts as a multinucleating donor, which leads to the formation of a ladder‐like cluster of [Cu(μ3‐OH)] units containing a total of two ligands, six copper(II) ions, four hydroxido ligands and eight trifluoroacetate ions. Two of the trifluoroacetate ions are non‐coordinating. Variable‐temperature magnetic susceptibility data are reported for this hexanuclear copper(II) cluster. Copper(I) complexes of 1 and 3 have been characterized and allowed to react with molecular oxygen, which caused the decomposition of the complexes. The IR spectra of the oxygenation products have bands at 1652 and 1632 cm–1, respectively, which are absent in the spectra of 1 and 3, suggesting that amine functions have been oxidized to imines.

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“…[53] and are given for 25°C and an ionic strength of 0.1  unless otherwise noted; abbreviation of ligands (see also Scheme 1): tetren: 1,4,7,10,13-pentaazatridecane, [15]aneN5: 1,4,7,10,13-pentaazacyclopentadecane, [16]aneN5: 1,4,7,10,13-pentaazacyclohexadecane, pydien: 1,9-bis(2-pyridyl)-2,5,8-triazanonane, pydpt: 1,11-bis(2-pyridyl)-2,6,10-triazaundecane.…”

Section: In Aqueous Solutionmentioning

confidence: 99%

The Coordination Chemistry of the Pentadentate 2,2,6,6‐Tetrakis(aminomethyl)‐4‐azaheptane (ditame)

et al. 2003

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A Tetraphosphane Imine Ligand Which Enforces Square‐Pyramidal Coordination

Cited by 15 publications

References 16 publications

Oxygen Delivery as a Limiting Factor in Modelling Dicopper(II) Oxidase Reactivity

Oxygen Delivery as a Limiting Factor in Modelling Dicopper(II) Oxidase Reactivity

Copper Complexes of “Superpodal” Amine Ligands and Reactivity Studies towards Dioxygen

The Coordination Chemistry of the Pentadentate 2,2,6,6‐Tetrakis(aminomethyl)‐4‐azaheptane (ditame)

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