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Lonnon DG Craig DC Colbran SB Bernhardt PV 《Dalton transactions (Cambridge, England : 2003)》2004,(5):778-787
Copper(II) bromide and chloride complexes of the new heptadentate ligand 2,6-bis(bis(2-pyridylmethyl)amino)methylpyridine (L) have been prepared. For the bromide complexes, chains of novel, approximately C2-symmetric, chiral [Cu2(L)Br2]2+ 'wedge-shaped' tectons are found. The links between the dicopper tectons and the overall chirality and packing of the chains are dictated by the bromide ion content, not the counter anion. In contrast, the chloride complexes exhibit linked asymmetric [Cu2(L)Cl3]+ tectons with distinct N3CuCl2 and N4CuCl2 centres in the solid. The overall structures of the dicopper bromide and chloride units persist in solution irrespective of the halide. The redox chemistry of the various species is also described. 相似文献
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Stephen B. Colbran Brian H. Robinson Jim Simpson 《Journal of organometallic chemistry》1984,265(2):199-204
The nitrosyl clusters PPN[YCCo3(CO)7(NO)] (Y = Me, Ph, COOH, (C5H5)Fe(C5H4)) have been prepared in high yield from the reaction of YCCo3(CO)9 with PPN(NO2) in THF, acetone or acetonitrile. Spectroscopic evidence indicates the structure of the nitrosyl anions is derived from that of YCCo3(CO)9 by the replacement of two CO ligands on one cobalt atom by a linear, terminal nitrosyl group. The nitrosyl metallates are extremely sensitive to oxidation and attempts to protonate the anions resulted in the reformation of the parent YCCo3(CO)9, molecules. The oxidative electrochemistry of the ferrocene complex, PPN[(C5H5)Fe(C5H4CCo3(CO)7(NO)] is also discussed. 相似文献
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Overtone spectrum of o, m and p-nitrobenzaldehydes and p-chlorobenzaldehyde has been studied in 2000–12000 cm−1 region. Vibrational frequencies and anharmonicity constants for aryl as well as alkyl CH stretch vibrations have been determined.
We have also determined the internuclear distances for the aryl CH bond in the different molecules. The small variation observed
in these distances is an indication of the substitution effect.
It is observed that in the case of p-disubstituted benzens, the shift in aryl CH bond is proportional to sum of the Hammet σ of the substituents. However in the
case of o-disubstituted benzenes it is only 80% of the para-substituted shift. 相似文献
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Bio‐Inspired Transition Metal–Organic Hydride Conjugates for Catalysis of Transfer Hydrogenation: Experiment and Theory
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Alex McSkimming Dr. Bun Chan Dr. Mohan M. Bhadbhade Dr. Graham E. Ball Prof. Stephen B. Colbran 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(7):2821-2834
Taking inspiration from yeast alcohol dehydrogenase (yADH), a benzimidazolium (BI+) organic hydride‐acceptor domain has been coupled with a 1,10‐phenanthroline (phen) metal‐binding domain to afford a novel multifunctional ligand ( L BI+) with hydride‐carrier capacity ( L BI++H?? L BIH). Complexes of the type [Cp*M( L BI)Cl][PF6]2 (M=Rh, Ir) have been made and fully characterised by cyclic voltammetry, UV/Vis spectroelectrochemistry, and, for the IrIII congener, X‐ray crystallography. [Cp*Rh( L BI)Cl][PF6]2 catalyses the transfer hydrogenation of imines by formate ion in very goods yield under conditions where the corresponding [Cp*Ir( L BI)Cl][PF6] and [Cp*M(phen)Cl][PF6] (M=Rh, Ir) complexes are almost inert as catalysts. Possible alternatives for the catalysis pathway are canvassed, and the free energies of intermediates and transition states determined by DFT calculations. The DFT study supports a mechanism involving formate‐driven Rh?H formation (90 kJ mol?1 free‐energy barrier), transfer of hydride between the Rh and BI+ centres to generate a tethered benzimidazoline (BIH) hydride donor, binding of imine substrate at Rh, back‐transfer of hydride from the BIH organic hydride donor to the Rh‐activated imine substrate (89 kJ mol?1 barrier), and exergonic protonation of the metal‐bound amide by formic acid with release of amine product to close the catalytic cycle. Parallels with the mechanism of biological hydride transfer in yADH are discussed. 相似文献
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Inside Cover: Bio‐Inspired Transition Metal–Organic Hydride Conjugates for Catalysis of Transfer Hydrogenation: Experiment and Theory (Chem. Eur. J. 7/2015)
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With the advent of medium and large gamma detector arrays, it is now possible to look at nuclear structure at high rotational
forces. The role of pairing correlations and their eventual breakdown, along with the shell effects have showed us the interesting
physics for nuclei at high spins — superdeformation, shape co-existence, yrast traps, alignments and their dramatic effects
on nuclear structure and so on. Nuclear structure studies have recently become even more exciting, due to efforts and possibilities
to reach nuclei far off from the stability valley. Coupling of gamma ray arrays with ‘filters’, like neutron wall, charged
particle detector array, gamma ray total energy and multiplicity castles, conversion electron spectrometers etc gives a great
handle to study nuclei produced online with ‘low’ cross-sections. Recently we studied, nuclei in mass region 80 using an array
of 8 germanium detectors in conjunction with the recoil mass analyser, HIRA at the Nuclear Science Centre and, most unexpectedly
came across the phenomenon of identical bands, with two quasi-particle difference. The discovery of magnetic rotation is another
highlight. Our study of light In nucleus, 107In brought us face to face with the ‘dipole’ bands. I plan to discuss some of
these aspects. There is also an immensely important development — that of the ‘radioactive ion beams’. The availability of
RIB, will probably very dramatically influence our ‘conventional’ concept of nuclear structure. The exotic shapes of these
exotic nuclei and some of their expected properties will also be touched upon. 相似文献
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Rare earth element substituted bismuth ferrites (BiFeO3) are of enormous importance as magnetoelectric materials. The polycrystalline samples of Bi
x
La1−x
FeO3 (x=0, 0.2, 0.4, 0.6, 0.8) were prepared by solid-state reaction using standard ceramic method. The single-phase formation of
these compounds was confirmed by X-ray diffraction (XRD) studies. The samples with x=0, 0.2, 0.4, 0.6 are found to be orthorhombic while the sample with x=0.8 is triclinic. The dielectric constant (ε′) and dissipation factor (tan δ) were measured in the frequency range 100 Hz
to 1 MHz at room temperature and as a function of temperature at certain fixed frequencies (1 kHz, 10 kHz, 100 kHz, 1 MHz).
All the samples showed dielectric dispersion. The dielectric constant with temperature shows a broad peak; the peak temperature
shifts with frequency which reflects the relaxor-type behavior. The peak above 600 K in the measured temperature range corresponds
to antiferromagnetic ordering temperature (Néel temperature). The broadness of the peak changes with composition. The ac conductivity
as well as ε′ are found to be maximum for the sample x=0.2 at room temperature. 相似文献