Nonheme Iron Mediated Oxidation of Light Alkanes with Oxone: Characterization of Reactive Oxoiron(IV) Ligand Cation Radical Intermediates by Spectroscopic Studies and DFT Calculations

Some ruthenium(III) complexes Ru(porp)(L)X and [Ru(porp)L2]X, (porp = dianion of octaethylporphyrin (OEP) or tetraphenylporphyrin (TPP); L = PPh3, P″Bu3; X = Br, Cl) have been prepared from the precursor complexes Ru(porp)L2 or Ru(porp)(CO)L using as oxidant the halogens, or air in the presence of the hydrogen halides. The X = PF6 salts can be made using Et3O+PF6− as oxidant. Ruthenium(II) porphyrin π-cation radical intermediates have sometimes been detected. The X-ray crystal structure of Ru(OEP)(PPh3)Br, the first reported for a ruthenium(III) porphyrin, reveals that metal is displaced 0.049 Å from the plane of the pyrrole N atoms towards the phosphine. The Ru(OEP)(py) Br and [Ru(OEP)(py)CH3CN]PF6 complexes have been synthesized from Ru(OEP)(CO)py. The ruthenium(III) complexes are low-spin as shown by magnetic and esr data. Optical and 1H nmr data, the latter showing large paramagnetic shifts, are also presented.

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Detection and Characterization of Mononuclear Pd(I) Complexes

10.26434/chemrxiv.12470945.v1 ◽

2020 ◽

Author(s):

Jia Luo ◽

Nigam P. Rath ◽

Liviu M. Mirica

Keyword(s):

Dft Calculations ◽

Chemical Reduction ◽

Spectroscopic Studies ◽

Oxidation States ◽

Chemical Transformations ◽

X Ray ◽

Tetradentate Ligands ◽

The Stability ◽

X Ray Absorption

Palladium is a versatile transition metal used to catalyze a large number of chemical transformations, largely due to its ability to access various oxidation states (0, I, II, III, and IV). Among these oxidation states, Pd(I) is arguably the least studied, and while dinuclear Pd(I) complexes are more common, mononuclear Pd(I) species are very rare. Reported herein are spectroscopic studies of a series of Pd(I) intermediates generated by the chemical reduction of Pd(II) precursors supported by the tetradentate ligands 2,11-dithia[3.3](2,6)pyridinophane (N2S2) and N,N’-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane (tBuN4): [(N2S2)PdII(MeCN)]2(OTf)4 (1), [(N2S2)PdIIMe]2(OTf)2 (2), [(N2S2)PdIICl](OTf) (3), [(N2S2)PdIIX](OTf)2 (X = tBuNC 4, PPh3 5), [(N2S2)PdIIMe(PPh3)](OTf) (6), and [(tBuN4)PdIIX2](OTf)2 (X = MeCN 8, tBuNC 9). In addition, a stable Pd(I) dinuclear species, [(N2S2)PdI(m-tBuNC)]2(ClO4)2 (7), was isolated upon the electrochemical reduction of 4 and structurally characterized. Moreover, the (tBuN4)PdI intermediates, formed from the chemical reduction of [(tBuN4)PdIIX2](OTf)2 (X = MeCN 8, tBuNC 9) complexes, were investigated by EPR spectroscopy, X-ray absorption spectroscopy (XAS), and DFT calculations, and compared with the analogous (N2S2)PdI systems. Upon probing the stability of Pd(I) species under various ligand environments (N2S2 and tBuN4), it is apparent that the presence of soft ligands such as tBuNC and PPh3 significantly improves the stability of Pd(I) species, which should make the isolation of mononuclear Pd(I) species possible.

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Detection and Characterization of Mononuclear Pd(I) Complexes

10.26434/chemrxiv.12470945 ◽

2020 ◽

Author(s):

Jia Luo ◽

Nigam P. Rath ◽

Liviu M. Mirica

Keyword(s):

Dft Calculations ◽

Chemical Reduction ◽

Spectroscopic Studies ◽

Oxidation States ◽

Chemical Transformations ◽

X Ray ◽

Tetradentate Ligands ◽

The Stability ◽

X Ray Absorption

Palladium is a versatile transition metal used to catalyze a large number of chemical transformations, largely due to its ability to access various oxidation states (0, I, II, III, and IV). Among these oxidation states, Pd(I) is arguably the least studied, and while dinuclear Pd(I) complexes are more common, mononuclear Pd(I) species are very rare. Reported herein are spectroscopic studies of a series of Pd(I) intermediates generated by the chemical reduction of Pd(II) precursors supported by the tetradentate ligands 2,11-dithia[3.3](2,6)pyridinophane (N2S2) and N,N’-di-tert-butyl-2,11-diaza[3.3](2,6)pyridinophane (tBuN4): [(N2S2)PdII(MeCN)]2(OTf)4 (1), [(N2S2)PdIIMe]2(OTf)2 (2), [(N2S2)PdIICl](OTf) (3), [(N2S2)PdIIX](OTf)2 (X = tBuNC 4, PPh3 5), [(N2S2)PdIIMe(PPh3)](OTf) (6), and [(tBuN4)PdIIX2](OTf)2 (X = MeCN 8, tBuNC 9). In addition, a stable Pd(I) dinuclear species, [(N2S2)PdI(m-tBuNC)]2(ClO4)2 (7), was isolated upon the electrochemical reduction of 4 and structurally characterized. Moreover, the (tBuN4)PdI intermediates, formed from the chemical reduction of [(tBuN4)PdIIX2](OTf)2 (X = MeCN 8, tBuNC 9) complexes, were investigated by EPR spectroscopy, X-ray absorption spectroscopy (XAS), and DFT calculations, and compared with the analogous (N2S2)PdI systems. Upon probing the stability of Pd(I) species under various ligand environments (N2S2 and tBuN4), it is apparent that the presence of soft ligands such as tBuNC and PPh3 significantly improves the stability of Pd(I) species, which should make the isolation of mononuclear Pd(I) species possible.

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Spectral and Structural Characterization of Metformin with Different Counter Anions: Comparative Analysis and DFT Calculations

Asian Journal of Chemistry ◽

10.14233/ajchem.2021.23422 ◽

2021 ◽

Vol 33 (11) ◽

pp. 2817-2825

Author(s):

Mohammed Alsawat ◽

Hamdy S. El-Sheshtawy ◽

Tariq Altalhi ◽

Amine Mezni ◽

Tushar Kumeria ◽

...

Keyword(s):

Dft Calculations ◽

Chemical Potential ◽

Crystal Packing ◽

Spectroscopic Studies ◽

Basis Set ◽

Chemical Hardness ◽

Spectroscopic Techniques ◽

Ft Ir ◽

Chemical Descriptors

The metformin perchlorate (MetH+·ClO4 −) with a new crystal structure was synthesized, characterized and comparatively studied with other metformin salts of Cl− and NO3 − by different spectroscopic techniques such as TGA-DSC and FT-IR as well as UV-visible spectroscopic studies. DFT calculations were performed by rwb97xd and 6-31G+(d,p) basis set for structure optimization and frequency calculations. Similar to MetH+·Cl−, the crystal packing of MetH+·ClO4 −andMetH+·NO3 − were stabilized by hexagonal hydrogen bond elongated network. The relative stability and reactivity of these salts were determined by exploring the DFT chemical descriptors such as chemical hardness, electronegativity, electronic chemical potential, electrophilicity and hardness. These calculations were employed to get the subset of variables that could categorize the metformin salts according to their reactivity.

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Green Synthesis and Spectroscopic Studies of Ag-rGO Nanocomposites for Highly Selective Mercury (II) Sensing

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681207666170705143629 ◽

2018 ◽

Vol 9 (1) ◽

pp. 101-108 ◽

Cited By ~ 1

Author(s):

Shubhangi J. Mane-Gavade ◽

Sandip R. Sabale ◽

Xiao-Ying Yu ◽

Gurunath H. Nikam ◽

Bhaskar V. Tamhankar

Keyword(s):

Green Synthesis ◽

Color Change ◽

Limit Of Detection ◽

Aqueous Media ◽

Suitable Condition ◽

Cost Effective ◽

Spectroscopic Studies ◽

Calibration Plot ◽

First Time

Introduction: Herein we report the green synthesis and characterization of silverreduced graphene oxide nanocomposites (Ag-rGO) using Acacia nilotica gum for the first time. Experimental: We demonstrate the Hg2+ ions sensing ability of the Ag-rGO nanocomposites form aqueous medium. The developed colorimetric sensor method is simple, fast and selective for the detection of Hg2+ ions in aqueous media in presence of other associated ions. A significant color change was noticed with naked eye upon Hg2+ addition. The color change was not observed for cations including Sr2+, Ni2+, Cd2+, Pb2+, Mg2+, Ca2+, Fe2+, Ba2+ and Mn2+indicating that only Hg2+ shows a strong interaction with Ag-rGO nanocomposites. Under the most suitable condition, the calibration plot (A0-A) against concentration of Hg2+ was linear in the range of 0.1-1.0 ppm with a correlation coefficient (R2) value 0.9998. Results & Conclusion The concentration of Hg2+ was quantitatively determined with the Limit of Detection (LOD) of 0.85 ppm. Also, this method shows excellent selectivity towards Hg2+ over nine other cations tested. Moreover, the method offers a new cost effective, rapid and simple approach for the detection of Hg2+ in water samples.

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New π -Donor Molecules with a Pyrazino Group and their Conducting Salts

Zeitschrift für Naturforschung B ◽

10.1515/znb-2001-0313 ◽

2001 ◽

Vol 56 (3) ◽

pp. 297-300 ◽

Cited By ~ 13

Author(s):

G. C. Papavassiliou ◽

Yohji Misaki ◽

Kazuko Takahashi ◽

Jun-ichi Yamada ◽

G. A. Mousdis ◽

...

Keyword(s):

Charge Transfer ◽

Cation Radical ◽

Charge Transfer Complexes ◽

Edge Group

Abstract The preparation and characterization of some π-donors with a pyrazine-edge-group as well as with tetrathiapentalene-, thiophene-, and dihydrobenzoselenophene-spacer-groups are de scribed. Some of these donors give conducting charge transfer complexes with TCNQ and/or cation radical salts with I3-, BF4-and PF6-as counter anions.

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