Dicopper cryptates with 1,1 and 1,3 bridging ligands: spectroscopic, magnetic and electrochemical properties
摘要:
The furan-based hexaiminocryptand L1, N[(CH2)2N=CHRCH=N(CH2)2]3N where R = furan-2,5-diyl, has been found to act as host for dicopper(I) and mu-hydroxo-dicopper(II). The corresponding octa-aminocryptand derivative L2 accommmodated dicopper(II) with hydroxide, imidazolate or azide bridging ligands. A single-crystal X-ray analysis of [Cu2L1[BF4]2 revealed trigonal-pyramidal co-ordination for Cu(I) together with a Cu ... Cu separation of 4.2 angstrom. The mu hydroxo-dicopper(II) cryptate [Cu2L2(OH)] [CF3SO3]2 was found to have trigonal-bipyramidal geometry, with a Cu ... Cu separation of 3.9 angstrom and the Cu-OH-Cu assembly close to linear. Effective magnetic exchange arising from collinear disposition of bridge O 2p(z) and copper(II) magnetic orbitals makes the hydroxo-bridged derivatives effectively diamagnetic.
Modulation of the CO<sub>2</sub> fixation in dinickel azacryptands
作者:F. Möller、L. Castañeda-Losada、J. R. C. Junqueira、R. G. Miller、M. L. Reback、B. Mallick、M. van Gastel、U.-P. Apfel
DOI:10.1039/c6dt04527h
日期:——
Different linker molecules within the dinickel azacryptand moiety show strong influence towards their CO2 coordination behaviour.
在二核氮杂环戊醚分子中,不同的连接分子对其CO₂配位行为产生强烈影响。
Cascade complexation: a single cyano bridge links a pair of Cu(ii) cations
作者:Andrew D. Bond、Sofia Derossi、Charles J. Harding、Eric J. L. McInnes、Vickie McKee、Christine J. McKenzie、Jane Nelson、Joanna Wolowska
DOI:10.1039/b504916d
日期:——
A series of structurally characterised μ-cyanodicopper(II) cryptates shows moderately strong antiferromagnetic interaction in the range −2J
= 150–200 cm−1, at the high end of the observed range for such assemblies. The lowest magnetic exchange coupling parameter is displayed where there is slight bending of the M–CN–M assembly, enforced by the constraints of cryptate encapsulation. Thermally accessible triplet EPR spectra are observed with zero-field splittings of the order of 0.13–0.14 cm−1, confirming collinear ground-state dz2 orbitals for Cu(II), consistent with their trigonal-bipyramidal coordination geometries.
The efficiency of a series of amino-azacryptands for encapsulation and extraction of the oxoanions pertechnetate and perrhenate from aqueous solution is investigated and compared with that of their open-chain counterparts. The aqueous formation constants for oxoanion association with the cryptands were determined by pH potentiometry and/or NMR, and X-ray analysis of single crystals provides evidence for encapsulation. The extractabilities could not be explained solely on the basis of ligand lipophilicity; the level of protonation also plays an important role.
研究了一系列氨基偶氮隐含物从水溶液中封装和萃取过硫酸盐和过铼酸盐氧阴离子的效率,并将其与开链对应物的效率进行了比较。通过 pH 电位法和/或核磁共振法测定了氧阴离子与隐晶质结合的水形成常数,单晶体的 X 射线分析提供了封装的证据。萃取能力不能仅根据配体的亲油性来解释,质子化水平也起着重要作用。
Halide ion inclusion into a dicopper(II) bistren cryptate containing ‘active’ 2,5-dimethylfuran spacers: The origin of the bright yellow colour
The inclusion of halide ions into a dicopper(II) bistren cryptate complex containing 2,5-dimethylfuran spacers has been investigated through spectrophotometric titration experiments in MeCN solution. X-ray diffraction studies on the 1: 1 chloride inclusion complex have shown that the encapsulated halide ion and the furan oxygen atoms lie at an interacting distance. Such an interaction perturbs the energy of the halide-to-copper(II) charge transfer transition, which is shifted to the visible region. As a consequence, an intense yellow colour develops on halide inclusion. Such a colour change is not observed on chloride or bromide inclusion into the dicopper(II) bistren cryptate containing spacers which are not capable to interact with the encapsulated halide and do not perturb the charge transfer transition, e. g. 1,3-xylyl fragments. (C) 2008 Elsevier B.V. All rights reserved.
Halide-Ion Encapsulation by a Flexible Dicopper(II) Bis-Tren Cryptate