On the K absorption edge investigations of copper in some complexes involving ON and SN donor ligands

Shah, M. C.; Shrivastava, B. D.; Pandeya, K. B.; Srivastava, K

doi:10.1088/0022-3719/16/18/029

Cited by 6 publications

(2 citation statements)

References 18 publications

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“…It is worth comparing the present values for the shift of the principal absorption maxima with the values reported by earlier workers for other copper(II) complexes. 9,10 The values for the present copper(II) complexes lie in the range 17.3-22.9 eV compared with earlier values 9,10 in the range 17.7-25.4 eV. Hence on the basis of this comparison, we may say that all the samples in the present investigation possess an oxidation state of C2.…”

Section: Shift Of the Principal Absorption Maximumsupporting

confidence: 62%

XANES studies of monosubstituted benzhydrazide complexes of copper

Joshi¹,

Shrivastava

Mishra

2004

X-Ray Spectrometry

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K x-ray absorption near-edge structure (XANES) studies were carried out on nine samples of monosubstituted benzhydrazide complexes of copper, viz. copper(II) benzhydrazide, o-, m-and phydroxybenzhydrazide, o-, m-and p-nitrobenzhydrazide and o-and p-chlorobenzhydrazide. These complexes are known for their pharmacological activity as antitubercular agents, antibacterial agents and as fungicides. In the three categories of substituted benzhydrazides the ionicity is found to increase in the order para > meta > ortho. Our studies revealed that the substituted complexes are less ionic than the parent complex. Among the three groups, hydroxy-substituted complexes are more ionic than nitro-and chloro-substituted hydrazides. Splitting of the principal absorption maximum .1s → 4p/ takes place in most of these complexes. The splitting into two components has been assigned to the transitions 1s → A * (4p z ) and 1s → B * (4p x , 4p y ). The estimated bandgap values for these complexes decrease in the order ortho > meta > para. The present studies indicate that as the chemical shift values increase in all the three groups, the bandgap energy values decrease.

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Section: Shift Of the Principal Absorption Maximumsupporting

confidence: 62%

XANES studies of monosubstituted benzhydrazide complexes of copper

Joshi¹,

Shrivastava

Mishra

2004

X-Ray Spectrometry

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“…The intense rising K-edge feature near 8987 eV for all three complexes is similar to that of solid [Cu(tsc) 2 Cl 2 ] (8987.08 eV), 66 which is associated with either highly covalent Cu(II)−S bonding or with multiple-scattering associated with squareplanar systems. 67 The intense rising edge feature near 8987 eV of [Cu(tsc) 2 ](NO 3 ) 2 is more intense than that of [Cu(tsc) 2 SO 4 ], consistent with its overall square-planar structure.…”

Section: ■ Resultsmentioning

confidence: 72%

Symmetry Breaking in Solution-Phase [Cu(tsc)₂(H₂O)₂]²⁺: Emergent Asymmetry in Cu–S Distances and in Covalence

Frank

Benfatto

2021

J. Phys. Chem. B

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The structure of aqueous Cu(II)-bis-thiosemicarbazide, [Cu(tsc)2]2+, is reported following EXAFS and MXAN analyses of the copper K-edge X-ray absorption (XAS) spectrum. The rising K-edge feature at 8987.1 eV is higher energy than those of crystalline models, implying unique electronic and structural solution states. EXAFS analysis (k = 2–13 Å–1; 2 × Cu–N = 2.02 ± 0.01 Å; 2 × Cu–S = 2.27 ± 0.01 Å; Cu–Oax = 2.41 ± 0.04 Å) could not resolve 5- versus 6-coordinate models. However, MXAN fits converged to an asymmetric broken symmetry 6-coordinate model with cis-disposed TSC ligands (Cu–Oax = 2.07 and 2.54 Å; Cu–N = 1.94 Å, 1.98 Å; Cu–S = 2.20 Å, 2.41 Å). Transition dipole integral evaluation of the sulfur K-edge XAS 1s → 3p valence transition feature at 2470.7 eV yielded a Cu–S covalence of 0.66 e–, indicating Cu1.34+. The high Cu–S covalence and short Cu–S bond in aqueous [Cu(tsc)2(H2O)2]2+ again contradict the need for a protein rack to explain the unique structure of the blue copper active site. MXAN models of dissolved Cu(II) complex ions have invariably featured broken centrosymmetry. The potential energy ground state for dissolved Cu(II) evidently includes the extended solvation field, providing a target for improved physical theory. A revised solvation model for aqueous Cu(II), |[Cu(H2O)5]·14H2O|2+, is presented.

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K-Absorption spectral studies of some copper(II) mixed-ligand complexes

Katare¹,

Joshi²,

Shrivastava

et al. 2000

X-Ray Spectrom.

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Edge shifts (ΔE), effective nuclear charge (Zeff) and % covalency for some copper(II) mixed‐ligand complexes were determined by investigating the copper K‐absorption edge using a Seifert x‐ray generator and a 0.4 m Cauchois‐type bent crystal transmission spectrograph. The shift values are suggestive of a parabolic dependence on Zeff of copper. Using the method of least squares, an expression ΔE = a + b(Zeff) + c(Zeff)2 was found to hold good for the dependence of ΔE on Zeff in the case of the complexes studied. Copyright © 2000 John Wiley & Sons, Ltd.

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On the K absorption edge investigations of copper in some complexes involving ON and SN donor ligands

Cited by 6 publications

References 18 publications

XANES studies of monosubstituted benzhydrazide complexes of copper

XANES studies of monosubstituted benzhydrazide complexes of copper

Symmetry Breaking in Solution-Phase [Cu(tsc)₂(H₂O)₂]²⁺: Emergent Asymmetry in Cu–S Distances and in Covalence

K-Absorption spectral studies of some copper(II) mixed-ligand complexes

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On the K absorption edge investigations of copper in some complexes involving ON and SN donor ligands

Cited by 6 publications

References 18 publications

XANES studies of monosubstituted benzhydrazide complexes of copper

XANES studies of monosubstituted benzhydrazide complexes of copper

Symmetry Breaking in Solution-Phase [Cu(tsc)2(H2O)2]2+: Emergent Asymmetry in Cu–S Distances and in Covalence

K-Absorption spectral studies of some copper(II) mixed-ligand complexes

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Product

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Symmetry Breaking in Solution-Phase [Cu(tsc)₂(H₂O)₂]²⁺: Emergent Asymmetry in Cu–S Distances and in Covalence