Exchange Coupling in Binuclear Manganese and Cobalt Complexes with the Tetraimido Sulfate Anion [S(NtBu)4]2–

The Dzhida ore field in the Zakamensk district of Buryatia features high concentration of mineralization within a small area. The Dzhida deposit is composed of complex ore. The ore field contains commercial-value primary deposits: Pervomai stockwork of molybdenum, Kholtoson tungsten lode and Inkur stockwork of tungsten. The Modonkul river catchment basin lies inside the Dzhida ore field. A real threat to the town of Zakamensk is created by manmade sand-bulk (old) tailings and slurry dump. By now, the concentrated flow of natural and man-made sand enters the low terrace and floodplain of the Modonkul river in the form of a talus train. This study is focused on the influence of the mine drainage effluent and the Inkur tributary on the water chemistry in the Modonkul river. 80 water samples were taken from the surface layer 0-0.5 m thick at five stations. Physicochemical indices of water were measured at the water sampling points, and the water chemistry was analyzed in a laboratory. In the background conditions, cations and anions in the Modonkul water chemistry range in decreasing order as follows: Са2+ > Mg2+ > Na++К+ и HCO - > SO 2- > Cl-. In the zone of mixture of natural and mine process water, the chemistry changes: from hydrocarbonate to sulfate (anion), from calcium-magnesium to sodium-calcium (cation). Downstream the natural chemistry changes to the hydrocabonate-sulfate composition, with prevailing content of calcium in cations. Iron content of water lowers 3-4 times after influx of mine effluents, while the contents of Mn, Zn, Co and Cd grow and then decrease downstream.

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Cobaloxime-Based Double Complex Salts as Efficient and Versatile Catalysts for the Light-Driven Hydrogen Evolution Reaction

10.26434/chemrxiv.11537661 ◽

2020 ◽

Author(s):

Elisabeth Hofmeister ◽

Jisoo Woo ◽

Tobias Ullrich ◽

Lydia Petermann ◽

Kevin Hanus ◽

...

Keyword(s):

Hydrogen Evolution ◽

Hydrogen Evolution Reaction ◽

Systematic Study ◽

Cobalt Complexes ◽

Spectroscopic Studies ◽

Double Complex ◽

Double Complex Salts ◽

Noble Metal Catalysts ◽

Reduction Potentials ◽

Complex Salts

Cobaloximes and their BF2-bridged analogues have emerged as promising non-noble metal catalysts for the photocatalytic hydrogen evolution reaction (HER). Herein we report the serendipitous discovery that double complex salts such as [Co(dmgh)2py2]+[Co(dmgBPh2)2Cl2]- can be obtained in good yields by treatment of commercially available [Co(dmgh)2pyCl] with triarylboranes. A systematic study on the use of such double complex salts and their single salts with simple counterions as photocatalysts revealed HER activities comparable or superior to existing cobaloxime catalysts and suggests ample opportunities for this compound class in catalyst/photosensitizer dyads and immobilized architectures. Preliminary electrochemical and spectroscopic studies indicate that one key advantage of these charged cobalt complexes is that the reduction potentials as well as the electrostatic interaction with charged photosensitizers can be tuned.

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Assessing the Calculation of Exchange Coupling Constants and Spin Crossover Gaps Using the Approximate Projection Model to Improve Density Function Calculations

10.26434/chemrxiv.7976474.v2 ◽

2019 ◽

Author(s):

Xianghai Sheng ◽

Lee Thompson ◽

Hrant Hratchian

Keyword(s):

Density Functional Theory ◽

Exchange Coupling ◽

Density Functional ◽

Spin Crossover ◽

Coupling Constants ◽

Spin Projection ◽

Coupling Constant ◽

Projection Model ◽

Functional Theory

This work evaluates the quality of exchange coupling constant and spin crossover gap calculations using density functional theory corrected by the Approximate Projection model. Results show that improvements using the Approximate Projection model range from modest to significant. This study demonstrates that, at least for the class of systems examined here, spin-projection generally improves the quality of density functional theory calculations of J-coupling constants and spin crossover gaps. Furthermore, it is shown that spin-projection can be important for both geometry optimization and energy evaluations. The Approximate Project model provides an affordable and practical approach for effectively correcting spin-contamination errors in molecular exchange coupling constant and spin crossover gap calculations.

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The influence of interlayer exchange coupling on magnetic ordering in Fe/V superlattices

Journal of Magnetism and Magnetic Materials ◽

10.1016/j.jmmm.2008.11.010 ◽

2009 ◽

Vol 321 (9) ◽

pp. 1214-1220 ◽

Cited By ~ 5

Author(s):

M. Marcellini ◽

M. Pärnaste ◽

B. Hjörvarsson ◽

G. Nowak ◽

H. Zabel

Keyword(s):

Exchange Coupling ◽

Magnetic Ordering ◽

Interlayer Exchange Coupling ◽

Interlayer Exchange

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Exchange Coupling of Transition-Metal Ions through Hydrogen Bonding: A Theoretical Investigation

Journal of the American Chemical Society ◽

10.1021/ja0178160 ◽

2002 ◽

Vol 124 (18) ◽

pp. 5197-5205 ◽

Cited By ~ 154

Author(s):

Cédric Desplanches ◽

Eliseo Ruiz ◽

Antonio Rodríguez-Fortea ◽

Santiago Alvarez

Keyword(s):

Hydrogen Bonding ◽

Transition Metal ◽

Metal Ions ◽

Theoretical Investigation ◽

Exchange Coupling ◽

Transition Metal Ions

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Paramagnetic solid-state NMR assignment and novel chemical conversion of the aldehyde group to dihydrogen ortho ester and hemiacetal moieties in copper(ii)- and cobalt(ii)-pyridinecarboxaldehyde complexes

RSC Advances ◽

10.1039/d1ra02512k ◽

2021 ◽

Vol 11 (33) ◽

pp. 20216-20231

Author(s):

Ayelén F. Crespi ◽

Verónica M. Sánchez ◽

Daniel Vega ◽

Ana L. Pérez ◽

Carlos D. Brondino ◽

...

Keyword(s):

Solid State ◽

Solid State Nmr ◽

Nmr Assignment ◽

Cobalt Complexes ◽

Chemical Conversion ◽

Aldehyde Group ◽

Ortho Ester ◽

Complex Chemical ◽

Chemical Functionalization

The complex chemical functionalization of the aldehyde group was elucidated in copper and cobalt complexes for 4- and 3-pyridinecarboxaldehyde ligands.

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