CH⋯Metal(II) axial interaction in planar complexes (metal = Cu, Pd) and implications for possible environmental effects of alkyl groups at biological copper sites

Yamauchi, Osamu; Yajima, Tatsuo; Fujii, Rie; Shimazaki, Yasuhisa; Yabusaki, Masanobu; Takani, Masako; Tashiro, Minoru; Motoyama, Takeshi; Kakuto, Mitsuhiro; Nakabayashi, Yasuo

doi:10.1016/j.jinorgbio.2007.11.022

Cited by 20 publications

(7 citation statements)

References 40 publications

(69 reference statements)

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“…The C6-H6C/ H6DÁ Á ÁCu1 vi angles are 112.8720 (3) and 109.287 (4) for H6C and H6D, respectively. These distances and bond angle values are in good agreement with other similar interactions found in the literature (Brookhart & Green, 1983;Braga et al, 1998;Yang et al, 2004;Yamauchi et al, 2008).…”

Section: Tablesupporting

confidence: 92%

Crystal structures of μ-oxalato-bis[azido(histamine)copper(II)] and μ-oxalato-bis[(dicyanamido)(histamine)copper(II)]

Liu

Abboud

2015

Acta Cryst E

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Section: Tablesupporting

confidence: 92%

Crystal structures of μ-oxalato-bis[azido(histamine)copper(II)] and μ-oxalato-bis[(dicyanamido)(histamine)copper(II)]

Liu

Abboud

2015

Acta Cryst E

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“…Although anagostic interactions are usually found in d 8 metals, they are occasionally associated with other systems such as Cu(II) (d 9 ) [72,73]. There are emerging discussions on the significance of such bonding [63] and possible applications in bio-active systems [74]. This provides an impetus for us to examine if such dual cinteractions from a mixed-ligand motif can be applied to stabilize non-d 8 systems.…”

Section: Resultsmentioning

confidence: 99%

Formation and structures of Pd(II) N,S-heterocyclic carbene-pyridyl mixed-ligand complexes

Yen

Koh

Huynh

et al. 2009

Journal of Organometallic Chemistry

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“…This deshielding effect exists whatever the metal atom, with varying intensities, and clearly indicates an effect of the complex on the hydrogen atoms that point toward the inside of the cavity (see the Supporting Information, SI4). It is therefore logical to attribute this shift to a CÀH···M interaction, [21] which indicates that the metal is buried right in the middle of the cavity. Thus, the chloride atom in 7 a·CuCl was replaced with a cyclopentadienyl (Cp) anion by the simple addition of NaCp.…”

mentioning

confidence: 99%

“…Variation of the NHC structure (imidazole versus benzimidazole) also induces a change in the chemical shift of this pair of hydrogen atoms (the signal for 8·AgCl is shifted 0.4 ppm downfield relative to the corresponding signal for 7 a·AgCl). It is therefore logical to attribute this shift to a CÀH···M interaction, [21] which indicates that the metal is buried right in the middle of the cavity. This C À H···M interaction was not described for previously reported CD-based metallocavitands, in which a CÀH···X interaction was invoked to explain the deshielding of the H-5 hydrogen atoms.…”

mentioning

confidence: 99%

NHC‐Capped Cyclodextrins (ICyDs): Insulated Metal Complexes, Commutable Multicoordination Sphere, and Cavity‐Dependent Catalysis

Guitet¹,

Zhang²,

Marcelo³

et al. 2013

Angew Chem Int Ed

137

117

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Metal centers associated with cavities have attracted much attention, mainly because of their resemblance to metalloenzymes.[1] Among concave molecules with a cavity, cyclodextrins (CDs) are unique owing to their natural occurrence, their hydrosolubility, and the structure of their cavity. Unlike any other cavity, in particular those based on aromatic rings, their interior is carpeted with hydrogen atoms, which confer hydrophobicity and introduce additional van der Waals interactions. Therefore, CDs are widely used to host hydrophobic molecules in polar solvents. The possibility of converting cyclodextrins into enzyme mimics very soon attracted the interest of scientists.[2] More specifically, for CDs to be used to mimic metalloenzymes, a metal must be attached to the CD scaffold. [3] Owing to the size of the cavity, two different ways to append the metal can be considered for the study of two different phenomena. First, the metal can be positioned at the entrance of the cavity to exploit the inclusion ability of the cavity in its interaction with a substrate and mimic the binding pocket of an enzyme (Figure 1 a).Second, the metal can be encapsulated inside the cavity to study the effect of confinement on its coordination sphere and chemical properties; this arrangement mimics the environment of a metal buried deeply within a folded protein (Figure 1 b).The first kind of design has been widely studied, often with the attachment of a metal-ligand unit through a single linkage.[3] Such structures can be used in a multitude of applications, for example, in catalysis.[4] However, for the metal center to be fixed directly above the cavity, double linkage of the metal was necessary. In the resulting so-called metal-capped CDs, [5,6] the metal ion is located right on top of the CD cavity.[7] The deepest position in which the metal has been placed so far intercepts the plane defined by the C-6 atoms of the sugar units. [8,9] This metal position leaves the cavity available for the inclusion of guests. The cavity can thus serve as a host for substrates (the interaction of which with the metal center can lead to an acceleration of the reaction rate [10] in analogy with an enzymatic reaction), as a probe for ligand exchange, [8] or as a second coordination sphere through C À H···X À M interactions. [11] For metallocyclodextrins of the second kind, in which the metal center occupies the middle of the cavity like an included guest, typically at the level of the H-5 atoms, only noncovalent inclusion complexes of metal ions have been described so far. Their electrochemical properties have been studied thoroughly, and electron transfer is thought not to involve the included complex, but the free portion of nonincluded metallic guest ions.[12] In other words, no studies on cyclodextrin complexes in which the metal ion is forced through covalent bonding to be included deep inside the Figure 1. In a metal-capped cyclodextrin, the cavity interacts either a) with the substrate or b) with the metal, depending on the depth of inclusion....

show abstract

CH⋯Metal(II) axial interaction in planar complexes (metal = Cu, Pd) and implications for possible environmental effects of alkyl groups at biological copper sites

Cited by 20 publications

References 40 publications

Crystal structures of μ-oxalato-bis[azido(histamine)copper(II)] and μ-oxalato-bis[(dicyanamido)(histamine)copper(II)]

Crystal structures of μ-oxalato-bis[azido(histamine)copper(II)] and μ-oxalato-bis[(dicyanamido)(histamine)copper(II)]

Formation and structures of Pd(II) N,S-heterocyclic carbene-pyridyl mixed-ligand complexes

NHC‐Capped Cyclodextrins (ICyDs): Insulated Metal Complexes, Commutable Multicoordination Sphere, and Cavity‐Dependent Catalysis

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