Effect of the chemical structure of an equatorial ligand on the spin crossover properties of the Fe(III) complex with 4-styrylpyridine axial ligands

2020 ◽  
Vol 152 (1) ◽  
pp. 014306 ◽  
Author(s):  
O. A. Turanova ◽  
M. Yu. Volkov ◽  
E. N. Frolova ◽  
L. Bazan ◽  
G. G. Garifzianova ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Spin Crossover ◽  
Axial Ligands ◽  
Equatorial Ligand

Ruthenium catalysts for water oxidation involving tetradentate polypyridine-type ligands

2015 ◽  
Vol 185 ◽  
pp. 87-104 ◽  
Author(s):  
Lianpeng Tong ◽  
Ruifa Zong ◽  
Rongwei Zhou ◽  
Nattawut Kaveevivitchai ◽  
Gang Zhang ◽  
...  
Keyword(s):  
Water Oxidation ◽  
Catalytic Performance ◽  
Ruthenium Catalysts ◽  
Oxidation States ◽  
Coordination Geometry ◽  
Tetradentate Ligand ◽  
Catalytic Behavior ◽  
Axial Ligands ◽  
Substituted Pyridines ◽  
Equatorial Ligand

A series of RuII complexes that behave as water oxidation catalysts were prepared involving a tetradentate equatorial ligand and two 4-substituted pyridines as the axial ligands. Two of these complexes were derived from 2,9-di-(pyrid-2′-yl)-1,10-phenanthroline (dpp) and examine the effect of incorporating electron-donating amino and bulky t-butyl groups on catalytic activity. A third complex replaced the two distal pyridines with N-methylimidazoles that are more electron-donating than the pyridines of dpp and potentially stabilize higher oxidation states of the metal. The tetradentate ligand 2-(pyrid-2′-yl)-6-(1′′,10′′-phenanthrol-2′′-yl)pyridine (bpy–phen), possessing a bonding cavity similar to dpp, was also prepared. The RuII complex of this ligand does not have two rotatable pyridines in the equatorial plane and thus shows different flexibility from the [Ru(dpp)] complexes. All the complexes showed activity towards water oxidation. Investigation of their catalytic behavior and electrochemical properties suggests that they may follow the same catalytic pathway as the prototype [Ru(dpp)pic2]2+ involving a seven-coordinated [RuIV(O)] intermediate. The influence of coordination geometry on catalytic performance is analyzed and discussed.

scholarly journals Temperature dependence of the spin state and geometry in tricobalt paddlewheel complexes with halide axial ligands

2018 ◽  
Vol 47 (46) ◽  
pp. 16798-16806
Author(s):  
Anandi Srinivasan ◽  
Xiaoping Wang ◽  
Rodolphe Clérac ◽  
Mathieu Rouzières ◽  
Larry R. Falvello ◽  
...  
Keyword(s):  
Temperature Dependence ◽  
Spin State ◽  
Spin Crossover ◽  
Molecular Geometry ◽  
Axial Ligand ◽  
Paddlewheel Complexes ◽  
Axial Ligands

A series of tricobalt EMACs with halide axial ligands demonstrate diverse spin-crossover behaviors as a function of the molecular geometry and the nature of the axial ligand.

Remarkable Steric Effects and Influence of Monodentate Axial Ligands L on the Spin-Crossover Properties oftrans-[FeII(N4ligand)L] Complexes

2007 ◽  
Vol 46 (10) ◽  
pp. 4079-4089 ◽  
Author(s):  
José Sánchez Costa ◽  
Kristian Lappalainen ◽  
Graham de Ruiter ◽  
Manuel Quesada ◽  
Jinkui Tang ◽  
...  
Keyword(s):  
Spin Crossover ◽  
Steric Effects ◽  
Axial Ligands

Effects of equatorial ligand bulk on the orientation of axial ligands in methyl organocobalt B12 models assessed by X-ray and NMR methods

2009 ◽  
Vol 362 (3) ◽  
pp. 993-1002 ◽  
Author(s):  
Scott J. Moore ◽  
Patrizia Siega ◽  
Rene J. Lachicotte ◽  
Lucio Randaccio ◽  
Patricia A. Marzilli ◽  
...  
Keyword(s):  
X Ray ◽  
Axial Ligands ◽  
Nmr Methods ◽  
Equatorial Ligand

A five-coordinate iron(III) porphyrin complex including a neutral axial pyridine N-oxide ligand

2019 ◽  
Vol 75 (6) ◽  
pp. 717-722
Author(s):  
Melanie A. Short ◽  
Roger D. Sommer ◽  
Alec J. Falzone ◽  
Tao Huang ◽  
Walter W. Weare ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Bond Length ◽  
Spin Crossover ◽  
Bond Angle ◽  
Organic Ligand ◽  
Binding Mode ◽  
Porphyrin Complex ◽  
Axial Ligands ◽  
Crossover Behavior ◽  
Porphyrin Core

While six-coordinate iron(III) porphyrin complexes with pyridine N-oxides as axial ligands have been studied as they exhibit rare spin-crossover behavior, studies of five-coordinate iron(III) porphyrin complexes including neutral axial ligands are rare. A five-coordinate pyridine N-oxide–5,10,15,20-tetraphenylporphyrinate–iron(III) complex, namely (pyridine N-oxide-κO)(5,10,15,20-tetraphenylporphinato-κ4 N,N′,N′′,N′′′)iron(III) hexafluoroantimonate(V) dichloromethane disolvate, [Fe(C44H28N4)(C5H5NO)][SbF6]·2CH2Cl2, was isolated and its crystal structure determined in the space group P\overline{1}. The porphyrin core is moderately saddled and the Fe—O—N bond angle is 122.08 (13)°. The average Fe—N bond length is 2.03 Å and the Fe—ONC5H5 bond length is 1.9500 (14) Å. This complex provides a rare example of a five-coordinate iron(III) porphyrin complex that is coordinated to a neutral organic ligand through an O-monodentate binding mode.

scholarly journals Synthesis, Spectroscopy and Electrochemistry of Cobalt(III) Schiff Base Complexes

2005 ◽  
Vol 2005 (3) ◽  
pp. 190-193 ◽  
Author(s):  
Ali Hossein Sarvestani ◽  
Abdollah Salimi ◽  
Sajjad Mohebbi ◽  
Rahman Hallaj
Keyword(s):  
Schiff Base ◽  
Structural Model ◽  
Ligand Substitution ◽  
Axial Ligand ◽  
Schiff Base Complexes ◽  
H Nmr ◽  
Reduction Potentials ◽  
Axial Ligands ◽  
D Orbitals ◽  
Equatorial Ligand

Three Co(III) complexes of the type [Co(chel)(PBu3)]ClO4.H2O, (chel = 5-BrSalen, 5-MeOSalen and 4-MeOSalen), were synthesised and characterised by elemental analysis, IR, UV-Vis and 1H NMR spectroscopy. In their electronic spectra, the absorptions between 550 and 750 nm of these complexes are attributable to the lowest d–d transition. The axial ligands affect this transition through a σ-intraction with the dz2 orbital and the equatorial ligands affect it by π-interaction with populated d-orbitals. On the basis of an electronic structural model, in which the dz2 orbital is populated in forming cobalt(II), it is suggested that equatorial ligand substitution affects the reduction potentials less than axial ligand substitution.

Inelastic Electron-Matter Interactions

1978 ◽  
Vol 36 (3) ◽  
pp. 259-267
Author(s):  
J. Silcox
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Chemical Structure ◽  
Inelastic Electron ◽  
Primary Concern ◽  
Unique Probe ◽  
Introductory Paper ◽  
Elastic Processes ◽  
Experimental Level ◽  
Inelastic Processes

In this introductory paper, my primary concern will be in identifying and outlining the various types of inelastic processes resulting from the interaction of electrons with matter. Elastic processes are understood reasonably well at the present experimental level and can be regarded as giving information on spatial arrangements. We need not consider them here. Inelastic processes do contain information of considerable value which reflect the electronic and chemical structure of the sample. In combination with the spatial resolution of the electron microscope, a unique probe of materials is finally emerging (Hillier 1943, Watanabe 1955, Castaing and Henri 1962, Crewe 1966, Wittry, Ferrier and Cosslett 1969, Isaacson and Johnson 1975, Egerton, Rossouw and Whelan 1976, Kokubo and Iwatsuki 1976, Colliex, Cosslett, Leapman and Trebbia 1977). We first review some scattering terminology by way of background and to identify some of the more interesting and significant features of energy loss electrons and then go on to discuss examples of studies of the type of phenomena encountered. Finally we will comment on some of the experimental factors encountered.

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