Spin-crossover in a homoleptic cobalt(ii) complex containing a redox-active NNO ligand

2016 ◽  
Vol 4 (3) ◽  
pp. 455-459 ◽  
Author(s):  
R. A. Taylor ◽  
A. J. Lough ◽  
M. T. Lemaire
Keyword(s):  
Magnetic Properties ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Cobalt Complex ◽  
Cobalt Complexes ◽  
Donor Ligands ◽  
Redox Active ◽  
Divalent Cobalt

We report the structural and variable temperature magnetic properties of divalent cobalt complex containing the ligand 1-(2-pyridylazo)-2-phenanthrol (papl). This complex provides a rare example of spin-crossover in cobalt complexes with redox-active NNO donor ligands.

scholarly journals Correction: Dinuclear cobalt complexes with a redox active biphenyl bridging ligand [Co2(BP)(tqa)2](PF6)2 (H4BP = 4,4′-bis(3-tert-butyl-1,2-catechol), tqa = tris(2-quinolylmethyl)amine): structure and magnetic properties

2021 ◽  
Author(s):  
Yusaku Suenaga ◽  
Takuto Mibu ◽  
Takashi Okubo ◽  
Masahiko Maekawa ◽  
Takayoshi Kuroda-Sowa ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Cobalt Complexes ◽  
Dalton Trans ◽  
Tert Butyl ◽  
Bridging Ligand ◽  
Redox Active ◽  
Amine Structure

Correction for ‘Dinuclear cobalt complexes with a redox active biphenyl bridging ligand [Co2(BP)(tqa)2](PF6)2 (H4BP = 4,4′-bis(3-tert-butyl-1,2-catechol), tqa = tris(2-quinolylmethyl)amine): structure and magnetic properties’ by Yusaku Suenaga et al., Dalton Trans., 2021, DOI: 10.1039/d1dt00995h.

Dinuclear Cobalt Complexes with Redox Active Biphenyl Bridging Ligand [Co2(BP)(tqa)2](PF6)2 (H4BP = 4,4’-bis(3-tert-butyl-1,2-catechol), tqa = tris(2-quinolylmethyl)amine): Structure and Magnetic Properties

2021 ◽  
Author(s):  
Yusaku Suenaga ◽  
Takuto Mibu ◽  
Takashi Okubo ◽  
Masahiko Maekawa ◽  
T. Kuroda-Sowa ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Cobalt Complexes ◽  
Tert Butyl ◽  
Bridging Ligand ◽  
Methyl Amine ◽  
Redox Active ◽  
Amine Structure

The biscatechol, H4BP (4,4’-bis(3-tert-butyl-1,2-catechol)) that connects two redox active catechol moieties directly was synthesized. Also, tpa (tris(2-pyridylmethyl)amine), bpqa (bis(2-pyridylmethyl)(2-quinolylmethyl)amine), pbqa ((2-pyridylmethyl)bis(2-quinolyl methyl)amine), and tqa (tris(2-quinolylmethyl)amine) were synthesized as terminal ligands...

Synthesis, crystal structure and magnetic properties of the complex [ReCl3(tppz)]·MeCN

RSC Advances ◽  
2015 ◽  
Vol 5 (123) ◽  
pp. 101616-101622 ◽  
Author(s):  
J. Palion-Gazda ◽  
I. Gryca ◽  
B. Machura ◽  
Francesc Lloret ◽  
Miguel Julve
Keyword(s):  
Crystal Structure ◽  
Magnetic Properties ◽  
Variable Temperature ◽  
Donor Ligands ◽  
Magnetic Data ◽  
Nitrogen Donor Ligands ◽  
X Ray ◽  
Nitrogen Donor

The paper reports the synthesis, X-ray structure and a deep analysis of the variable-temperature magnetic data of the new complex [ReCl3(tppz)]·MeCN being a very scarce example of mononuclear Re(iii) complexes incorporating nitrogen donor ligands.

Mixed-Valent Polynuclear Cobalt Complexes Incorporating Tetradentate Phenoxyamine Ligands

2009 ◽  
Vol 62 (9) ◽  
pp. 1124 ◽  
Author(s):  
Joo Chuan Ang ◽  
Yanyan Mulyana ◽  
Chris Ritchie ◽  
Rodolphe Clérac ◽  
Colette Boskovic
Keyword(s):  
Variable Temperature ◽  
Cobalt Complexes ◽  
Antiferromagnetic Coupling ◽  
The Novel ◽  
X Ray Diffraction ◽  
Susceptibility Data ◽  
Trigonal Bipyramidal ◽  
Quantum Numbers ◽  
Spin Quantum ◽  
Divalent Cobalt

The new potentially tetradentate ligand precursor 2-[(bis(2-hydroxyethyl)amino)methyl]-4,6-bis-tert-butylphenol (H3L) has been synthesized and characterized. The reaction of H3L with cobalt(ii) acetate has afforded the novel mixed-valent tetra- and pentanuclear cobalt complexes [CoII2CoIII2(OAc)2(L)2(HL)] (1) and [CoIICoIII4(OAc)2(L)4] (2). Single-crystal X-ray diffraction studies of these complexes indicate different coordination geometries for the divalent cobalt centres in each complex, with distorted trigonal bipyramidal and distorted tetrahedral coordination evident in 1 and 2, respectively. The variable temperature magnetic susceptibility data for complex 1 reveal behaviour dominated by antiferromagnetic coupling between the two cobalt(ii) centres. Their approximate trigonal bipyramidal coordination geometries give rise to a 4A′2 ground term, allowing a spin-only treatment assuming local spin quantum numbers of Si = 3/2. Fitting the data to the Heisenberg exchange Hamiltonian (Ĥex = –2JS·1S2) results in J = –6.9(1) cm–1 and g = 2.30(5).

Iron(II) complexes containing thiophene-substituted “bispicen” ligands — Spin-crossover, ligand rearrangements, and ferromagnetic interactions

2010 ◽  
Vol 88 (9) ◽  
pp. 954-963 ◽  
Author(s):  
Haojin Cheng ◽  
Brandon Djukic ◽  
Hilary A. Jenkins ◽  
Serge I. Gorelsky ◽  
Martin T. Lemaire
Keyword(s):  
Magnetic Properties ◽  
Density Functional ◽  
Spin Crossover ◽  
Variable Temperature ◽  
Density Functional Theory Calculations ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Magnetic Analysis ◽  
Ferromagnetic Chain ◽  
Ferromagnetic Interactions

The synthesis and characterization of three new tetradentate “bispicen-type” ligands containing a substituted thiophene heterocycle are described [2,5-thienyl substituents = H (7), Ph (8), or 2-thienyl (9)]. Iron(II) bis(thiocyanate) coordination complexes containing 7–9 were prepared, and the electronic and variable-temperature magnetic properties of complexes containing 7 (10) and 9 (12) are described. Complex 10 features a gradual and incomplete spin crossover in the solid state, and 12 remains high-spin over the entire temperature range. Complex 11 is extremely unstable and rearranges to another iron(II) complex (13), which was structurally characterized. The temperature-dependent magnetic properties of 13 are described as a one-dimensional ferromagnetic chain, with interchain antiferromagnetic interactions and (or) zero-field splitting dominant at low temperatures. The magnetic analysis is corroborated by the molecular packing and density functional theory calculations, which suggest intermolecular interactions between coordinated thiocyanate ligands bearing a significant spin density.

Single crystal to single crystal transformation of spin-crossover coordination polymers from 3D frameworks to 2D layers

2021 ◽  
Vol 9 (15) ◽  
pp. 5082-5087
Author(s):  
Yu Gong ◽  
Wang-Kang Han ◽  
Hui-Shu Lu ◽  
Qing-Tao Hu ◽  
Huan Tu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Single Crystal ◽  
Coordination Polymers ◽  
Ligand Exchange ◽  
Spin Crossover ◽  
Metal Organic Frameworks ◽  
Crystal Transformation ◽  
Metal Organic

New Hofmann-type metal–organic frameworks display rare and complete ligand exchange induced single crystal to single crystal transformations from 3D frameworks to 2D layers, accompanied by magnetic properties transition from two-step SCO behavior to hysteretic SCO behavior.

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.

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