Squeezing the [Cu−OH···H<sub>2</sub>O−Cu]<sup>3+</sup> Bridge by Cryptate Encapsulation

Bond, Andrew D.; Derossi, Sofia; Jensen, Frank; Larsen, Frank B.; McKenzie, Christine J.; Nelson, Jane

doi:10.1021/ic0505091

Cited by 25 publications

(24 citation statements)

References 23 publications

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“…[18] A recent communication, [19] the results of which, however, we have been unable to replicate, [20] reports quantitative conversion of MeCN to CN À within the analogous pxylene spaced dicopper cryptate.…”

Section: Resultsmentioning

confidence: 66%

Ferromagnetic Interaction in μ_1,3‐Cyanamido‐Derived Copper(II) Cryptates

Escuer

Kee

Nelson

et al. 2004

Chemistry A European J

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The reaction of dinuclear copper(II) cryptates with calcium cyanamide, CaNCN, and sodium dicyanamide, Na[N(CN)(2)] results in dinuclear compounds of formulae [Cu(2)(HNCN)(R3Bm)](ClO(4))(3) (1), [Cu(2)(dca)(R3Bm)](ClO(4))(3)4H(2)O (2), and [Cu(2)(NCNCONH(2))(R3Bm)](CF(3)SO(3))(3) (3), in which R3Bm=N[(CH(2))(2)NHCH(2)(C(6)H(4)-m)CH(2)NH(CH(2))(2)](3)N and dca=dicyanamido ligand (NCNCN(-)). The X-ray diffraction analysis reveals for both 1 and 3 a dinuclear entity in which the copper atoms are bridged by means of the -NCN- unit. The molar magnetic susceptibility measurements of 1-3 in the 2-300 K range indicate ferromagnetic coupling. The calculated J values, by using theoretical methods based on density functional theory (DFT) are in excellent agreement with the experimental data. Catalytic hydration of a nitrile to an amide functional group is assumed responsible for the formation of 3 from a mu(1,3)-dicyanamido ligand.

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Section: Resultsmentioning

confidence: 66%

Ferromagnetic Interaction in μ_1,3‐Cyanamido‐Derived Copper(II) Cryptates

Escuer

Kee

Nelson

et al. 2004

Chemistry A European J

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“…The structures of 5 and [Co 2 L(OH)(OH 2 )] 3+ [9a] illustrate the axial flexibility of the cryptate ligand. The Cu ⋅⋅⋅ Cu and Co ⋅⋅⋅ Co distances of 7.013(1) Å in 5 and 6.482(2) Å in [Co 2 L(OH)(OH 2 )] 3+ are substantially longer than the Cu ⋅⋅⋅ Cu separation in [Cu 2 L(OH)(OH 2 )] 3+ (6.121(1) Å),8a that is, the Cu ⋅⋅⋅ Cu separation in [Cu 2 L] 4+ can be expanded to encapsulate different sizes of guest molecules within its cavity, and a squeezing effect does not exist in [Cu 2 L] 4+ .…”

Section: Resultsmentioning

confidence: 95%

“…The CuN (bridgehead) distances (1.991(5) and 1.999(5) Å) are close to the CuO distances (1.996(4) and 1.998(4) Å), which are shorter than the other CuN distances (2.098(5)–2.205(5) Å). The O1W ⋅⋅⋅ O2W distance of 3.032 Å is longer than the O1 ⋅⋅⋅ O1′ separation of 2.665(6) Å in [Co 2 L(OH)(OH 2 )] 3+ ,9a and much longer than the O1 ⋅⋅⋅ O1′ separation of 2.325(9) Å in [Cu 2 L(OH)(OH 2 )](ClO 4 ) 3 ( 6 ), in which the axial positions of the two Cu II ions are occupied by OH − and H 2 O, respectively 8a. The short O ⋅⋅⋅ O separation in [Cu 2 L(OH)(OH 2 )] 3+ was attributed to cryptate encapsulation squeezing the bridge 8a.…”

Section: Resultsmentioning

confidence: 96%

“…The O1W ⋅⋅⋅ O2W distance of 3.032 Å is longer than the O1 ⋅⋅⋅ O1′ separation of 2.665(6) Å in [Co 2 L(OH)(OH 2 )] 3+ ,9a and much longer than the O1 ⋅⋅⋅ O1′ separation of 2.325(9) Å in [Cu 2 L(OH)(OH 2 )](ClO 4 ) 3 ( 6 ), in which the axial positions of the two Cu II ions are occupied by OH − and H 2 O, respectively 8a. The short O ⋅⋅⋅ O separation in [Cu 2 L(OH)(OH 2 )] 3+ was attributed to cryptate encapsulation squeezing the bridge 8a. The structures of 5 and [Co 2 L(OH)(OH 2 )] 3+ [9a] illustrate the axial flexibility of the cryptate ligand.…”

Section: Resultsmentioning

confidence: 96%

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Mechanistic Studies of CC Bond Cleavage of Nitriles by Dinuclear Metal Cryptates

Yang

Zhuang

et al. 2009

Chemistry A European J

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We previously reported that dinuclear copper(II) cryptate [Cu(2)L](4+) cleaves the C-C bond of acetonitrile at room temperature to produce a cyano-bridged dinuclear cryptate and methanol, whereby the reaction mechanism has not yet become clear. We have now systemically investigated this reaction, and four cryptates, [Cu(2)L](ClO(4))(4) (1), [Zn(2)L](ClO(4))(4) (2), [Cu(2)L(H(2)O)(2)](CF(3)SO(3))(4) (5), and [Cu(2)L(OH)(OH(2))](ClO(4))(3) (6) are reported here. Cryptates 1 and 2 can cleave the C--C bonds of acetonitrile, propionitrile, and benzonitrile at room temperature under open atmospheric conditions to give cyano-bridged cryptates [Cu(2)L(CN)](ClO(4))(3) (3) and [Zn(2)L(CN)](ClO(4))(3) (4), respectively, and the corresponding alcohol. In contrast, 5 and 6 do not show any C-C bond activation of nitriles, as the interior axial positions of Cu(II) in 5 and 6 are occupied by water/OH(-). The C-C bond cleavage of (S)-(+)-2-methylbutyronitrile by 2 produced (R)-(-)-2-butanol only; that is, the cleavage reaction proceeds through an S(N)2 pathway (Walden inversion).

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“…[2] Diese Beobachtung wurde allerdings von Nelson und Mitarbeitern infrage gestellt, da sie diese Ergebnisse trotz detaillierter Untersuchungen nicht reproduzieren konnten. [3] Unsere eigenen Studien an verwandten Kupfer-Komplexen [4] führen uns allerdings zu der Schlussfolgerung, dass Cyanid tatsächlich entstehen könnte, wenn die erforderlichen Reaktionsbedingungen exakt eingehalten werden (den postulierten Reaktionsmechanismus halten wir allerdings für falsch). Erst kürzlich wurde das Auftreten einer solchen Reaktion von Karlin et al nachgewiesen: Sie demonstrierten, dass ein zweikerniger Kupfer(I)-Komplex mit einem Phenol-Derivat des von uns bereits früher vorgestellten Liganden 1,3-Bis-[bis(2-pyridylmethyl)amino]benzol (1,3-tpbd) [5] während der Oxidation mit Sauerstoff eine Hydroxylierung des NitrilSubstrats unter Bildung von Cyanid und Aldehyd bewirkt.…”

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