scholarly journals Electron-Spin Structure and Metal–Ligand Bonding in Open-Shell Systems from Relativistic EPR and NMR: A Case Study of Square-Planar Iridium Catalysts

2018 ◽  
Vol 15 (1) ◽  
pp. 201-214 ◽  
Author(s):  
Pankaj L. Bora ◽  
Jan Novotný ◽  
Kenneth Ruud ◽  
Stanislav Komorovsky ◽  
Radek Marek
Keyword(s):  
Electron Spin ◽  
Spin Structure ◽  
Open Shell ◽  
Iridium Catalysts ◽  
Square Planar ◽  
Metal Ligand

Interaction of ditertiary phosphines with phenyl- and 1-naphthyldithiocarbamatonickel(II)

1985 ◽  
Vol 50 (6) ◽  
pp. 1383-1390
Author(s):  
Aref A. M. Aly ◽  
Ahmed A. Mohamed ◽  
Mahmoud A. Mousa ◽  
Mohamed El-Shabasy
Keyword(s):  
Thermal Analysis ◽  
Powder Diffraction ◽  
Spin Structure ◽  
Magnetic Measurements ◽  
Mixed Ligand ◽  
Mixed Ligand Complexes ◽  
X Ray ◽  
Square Planar

The synthesis of the following mixed ligand complexes is reported: [Ni(phdtc)2(dpm)2], [Ni(phdtc)2(dpe)2], [Ni(phdtc)2(dpp)3], [Ni(1-naphdtc)2(dpm)2], [Ni(1-naphdtc)2], and [Ni(1-naphdtc)2(dpp)2], where phdtc = PhNHCSS-, 1-naphdtc = 1-NaPhNHCSS-, dpm = Ph2PCH2PPh2, dpe = Ph2P(CH2)2PPh2, and dpp = Ph2P(CH2)3PPh2. The complexes are characterised by microanalysis, IR and UV-Vis spectra, magnetic measurements, conductivity, X-ray powder diffraction, and thermal analysis. All the mixed ligand complexes are diamagnetic, and thus a square-planar or square-pyramidal (low-spin) structure was proposed for the present complexes.

scholarly journals Ligand-Mediated Spin State Changes in a Cobalt-Dipyrrin-Bisphenol Complex

2020 ◽  
Author(s):  
Nicolaas P. van Leest ◽  
Wowa Stroek ◽  
Maxime A. Siegler ◽  
Jarl Ivar van der Vlugt ◽  
Bas de Bruin
Keyword(s):  
Cobalt Complex ◽  
Closed Shell ◽  
Open Shell ◽  
Triplet Ground State ◽  
Redox Active Ligand ◽  
Redox Active ◽  
Square Planar ◽  
Amine Adducts ◽  
Meso Position ◽  
Electronic Ground

ABSTRACT: The influence of a redox-active ligand on spin changing events induced by coordination of exogenous donors is investigated within the cobalt complex <b>[Co<sup>II</sup>(DPP<sup>•2‒</sup>)]</b>, bearing a redox-active <b>DPP<sup>2‒</sup></b> ligand (DPP = dipyrrin-bis-(<i>o,p</i>-di-tert-butylphenolato) with a pentafluorophenyl moiety on the meso-position. This square planar complex was subjected to coordination of THF, pyridine, tBuNH<sub>2</sub> and AdNH<sub>2</sub> (Ad = 1‑adamantyl), and the resulting complexes were analyzed with a variety of experimental (XRD, NMR, UV-Vis, HRMS, SQUID, Evans’ method) and computational (DFT, NEVPT2-CASSCF) techniques to elucidate the respective structures, spin states and orbital compositions of the corresponding octahedral bis-donor adducts, relative to <b>[Co<sup>II</sup>(DPP<sup>•2‒</sup>)]</b>. This starting species is best described as an open-shell singlet complex containing a <b>DPP<sup>•2‒</sup></b> ligand radical that is antiferromagnetically coupled to a low-spin (S = ½) cobalt(II) center. The redox-active <b>DPP<sup>n‒</sup></b> ligand plays a crucial role in stabilizing this complex, and in its facile conversion to the triplet THF-adduct <b>[Co<sup>II</sup>(DPP<sup>•2‒</sup>)(THF)<sub>2</sub>]</b> and closed-shell singlet pyridine and amine adducts <b>[Co<sup>III</sup>(DPP<sup>3‒</sup>)(L)<sub>2</sub>]</b> (L = py, tBuNH<sub>2</sub> or AdNH<sub>2</sub>). Coordination of the weak donor THF to <b>[Co<sup>II</sup>(DPP<sup>•2-</sup>)]</b> changes the orbital overlap between the <b>DPP<sup>•2‒</sup></b> ligand radical π-orbitals and the cobalt(II) metalloradical d-orbitals, which results in a spin-flip to the triplet ground state without changing the oxidation states of the metal or <b>DPP<sup>•2‒</sup></b> ligand. In contrast, coordination of the stronger donors pyridine, tBuNH<sub>2</sub> or AdNH<sub>2</sub> induces metal-to-ligand single-electron transfer, resulting in formation of low-spin (S = 0) cobalt(III)-complexes <b>[Co<sup>III</sup>(DPP<sup>3‒</sup>)(L)<sub>2</sub>]</b> containing a fully reduced <b>DPP<sup>3‒</sup></b> ligand, thus explaining their closed-shell singlet electronic ground states.

scholarly journals Open-shell Donors and Closed-shell Acceptors in Organic Solar Cells

2021 ◽  
Author(s):  
Zhongxin Chen ◽  
Yuan Li ◽  
Wenqiang Li ◽  
Weiya Zhu ◽  
Miao Zeng ◽  
...  
Keyword(s):  
Solar Cells ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Organic Solar Cells ◽  
Ground State ◽  
Variable Temperature ◽  
Closed Shell ◽  
Open Shell ◽  
Singlet Ground State ◽  
Spin Resonance

The active materials of organic solar cells are widely recognized to show closed-shell singlet ground state and their electron spin resonance signals are attributed to the defects and impurities. Herein, we disclose the inherent open-shell singlet ground state of donors and the closed-shell structure of acceptors via the combination of variable temperature NMR, electron spin resonance, superconducting quantum interference device and theoretical calculation, providing a new perspective to understand the intrinsic molecular structure in organic solar cells.

Closed-shell and open-shell square-planar iridium nitrido complexes

2012 ◽  
Vol 4 (7) ◽  
pp. 552-558 ◽  
Author(s):  
Markus G. Scheibel ◽  
Bjorn Askevold ◽  
Frank W. Heinemann ◽  
Edward J. Reijerse ◽  
Bas de Bruin ◽  
...  
Keyword(s):  
Closed Shell ◽  
Open Shell ◽  
Nitrido Complexes ◽  
Square Planar

scholarly journals Application of data-based mechanistic modelling for flood forecasting at multiple locations in the Eden catchment in the National Flood Forecasting System (England and Wales)

2013 ◽  
Vol 17 (1) ◽  
pp. 177-185 ◽  
Author(s):  
D. Leedal ◽  
A. H. Weerts ◽  
P. J. Smith ◽  
K. J. Beven
Keyword(s):  
Warning System ◽  
Open Shell ◽  
Flood Forecasting ◽  
Mechanistic Modelling ◽  
Forecasting Models ◽  
Forecasting System ◽  
Environment Agency ◽  
The Uk ◽  
Modelling Approach

Abstract. The Delft Flood Early Warning System provides a versatile framework for real-time flood forecasting. The UK Environment Agency has adopted the Delft framework to deliver its National Flood Forecasting System. The Delft system incorporates new flood forecasting models very easily using an "open shell" framework. This paper describes how we added the data-based mechanistic modelling approach to the model inventory and presents a case study for the Eden catchment (Cumbria, UK).

scholarly journals Nuclear-spin-pattern control of electron-spin dynamics in a series of V(iv) complexes

2019 ◽  
Vol 10 (36) ◽  
pp. 8447-8454 ◽  
Author(s):  
Cassidy E. Jackson ◽  
Chun-Yi Lin ◽  
Spencer H. Johnson ◽  
Johan van Tol ◽  
Joseph M. Zadrozny
Keyword(s):  
Spin Relaxation ◽  
Electron Spin ◽  
Nuclear Spin ◽  
Spin Dynamics ◽  
Relaxation Times ◽  
Open Shell ◽  
Pattern Control ◽  
Electron Spin Dynamics

This report details how the design of specific nuclear-spin patterns on ligands modulates spin-relaxation times in a set of open-shell vanadium(iv) complexes.

Enhancement of Second Hyperpolarizabilities in Open-Shell Singlet Slipped-Stack Dimers Composed of Square Planar Nickel Complexes Involvingo-Semiquinonato Type Ligands

2011 ◽  
Vol 115 (6) ◽  
pp. 1117-1124 ◽  
Author(s):  
Hitoshi Fukui ◽  
Yasuteru Shigeta ◽  
Masayoshi Nakano ◽  
Takashi Kubo ◽  
Kenji Kamada ◽  
...  
Keyword(s):  
Nickel Complexes ◽  
Open Shell ◽  
Square Planar
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