Paramagnetic NMR Spectroscopy as a Tool for Studying the Electronic Structures of Lanthanide and Transition Metal Complexes

INEOS OPEN ◽  
2020 ◽  
Vol 2 (5) ◽  
pp. 153-162
Author(s):  
A. A. Pavlov ◽  
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Electronic Structures ◽  
Paramagnetic Nmr

scholarly journals High-Spin Cobalt(II) Complex with Record-Breaking Anisotropy of the Magnetic Susceptibility According to Paramagnetic NMR Spectroscopy Data

2021 ◽  
Vol 47 (1) ◽  
pp. 10-16
Author(s):  
Ya. A. Pankratova ◽  
Yu. V. Nelyubina ◽  
V. V. Novikov ◽  
A. A. Pavlov
Keyword(s):  
Magnetic Susceptibility ◽  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Single Molecule ◽  
Functional Materials ◽  
Medical Diagnostics ◽  
Paramagnetic Nmr ◽  
Single Molecule Magnets

Abstract The tetrahedral cobalt(II) complex [CoL2](HNEt3)2 (I), where L is 1,2-bis(methanesulfonamido)benzene, exhibiting the properties of a single-molecule magnet is synthesized and characterized. The electronic structure parameters of complex I are determined by paramagnetic NMR spectroscopy. They completely reproduce the results of less available methods of studying single-molecule magnets. The value of axial anisotropy of the magnetic susceptibility estimated for complex I (Δχax = 34.5 × 10–32 m3 at 20°C) is record-breaking among all transition metal complexes studied by the NMR method, which provides wide possibilities for the use of complex I as a paramagnetic label for structural biology or as a contrast agent and even a temperature sensor for medical diagnostics. The data obtained indicate the advantages of paramagnetic NMR spectroscopy as a method of investigation of the magnetic properties and electronic structures of highly anisotropic transition metal complexes, which are precursors of many functional materials.

Transition Metal Complexes with Sulphur Ligands, Part 151 [1]. Ligand Enforced Configurations and Low-Spin States of [FeNS4] Cores in [FeII(L)('pyS4')] Complexes with σ and σ-π Ligands (L = N2H4, pyridine, PMe3, PnPr3; 'pyS4'2- = 2,6-bis(2-mercaptophenylthiomethyl)pyridine (2-))

2001 ◽  
Vol 56 (7) ◽  
pp. 581-588 ◽  
Author(s):  
Dieter Sellmann ◽  
Nicole Blum ◽  
Frank W. Heinemann
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Magnetic Measurements ◽  
Spin States ◽  
X Ray ◽  
Structure Determinations

The reactions of [Fe('pyS4')]2 with PMe3 , PnPr3 , N2H4 and pyridine afforded mononuclear [Fe(L)('pyS4')] complexes with L = PMe3 ( 1 ), PnPr3 (2 ), N2H4 (3) and pyridine (4). NMR spectroscopy, magnetic measurements and X-ray structure determinations revealed that all complexes exhibit frans-thiolate donors and low-spin FeII centres, irrespective of the σ-π or σ ligand character of L. In this regard, the properties of [Fe(L)('pyS4')] complexes strongly contrast with those of [Fe(L)('NHS4')] complexes ('NHS4'2- = 2 ,2 '-bis(2 -mercaptophenylthio)- diethylamine(2 -)) and indicate that the rigid py(CH2)2 entity of the 'pyS42- ligand is able to enforce trans configurations and low-spin states of complexes with [FeNS4 ] cores. In spite of their diamagnetism, confirming the absence of antibonding electrons, all complexes 1 to 4 are highly reactive and rapidly exchange their L ligands for CO to give [Fe(CO)('pyS4')]. Evidence was obtained that the oxidation of [Fe(N'-H4)('pyS4')] (3) yields the diazene complex [μ-N2 H2 {Fe('pyS4’)}2] (5).

Gehinderte Ligandbewegungen in Übergangsmetallkomplexen, XXXI [1]. Synthese und Dynamik von Acetyl-carbonyl-η5-cyclopentadienyl-η4-dien-wolfram-Komplexen / Hindered Ligand Movements in Transition Metal Complexes, XXXI [1]. Syntheses and Dynamics of Acetyl-carbonyl-η5-cyclopentadienyl-η4-diene-tungsten Complexes

1986 ◽  
Vol 41 (5) ◽  
pp. 599-605 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Kurt Nist ◽  
Joachim Kögler
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Conjugated Dienes ◽  
The Other ◽  
Molecular Plane ◽  
H Nmr ◽  
Tungsten Complexes ◽  
Diene Ligands

Tricarbonyl-η5-cyclopentadienyl-methyl-tungsten (1) reacts upon UV irradiation with conjugated dienes, like 1,3-butadiene (2), E-1,3-pentadiene (3), 2-methyl-1,3-butadiene (4), 2,3-dimethyl-1,3- butadiene (5), 1,3-cyclopentadiene (6) and 1,3-cyclohexadiene (7), to give the corresponding, quasisquare- pyramidal [(η5-C5H5)W(CO)(COCH3)(η4-diene)] complexes (8-13). With the unsymmetrically substituted dienes 3 and 4, only one of the possible diastereotopic complexes are obtained. At 200 to 230 K, 8-12 show two isomers, which are distinguished by the orientations (o or u) of the diene with respect to the other ligands. The interconversion of the o- and u-isomers was studied by dynamic 1H NMR spectroscopy and is explained by an intramolecular ±180° rotation of the diene ligands in the molecular plane. The barriers o f activation ⊿G* 300 are between 57.8 and 61.0 ± 1 kJ/mol.

Gehinderte Ligandbewegungen in Übergangsmetallkomplexen, XIX [1]. Oktaedrische Wolfram-Olefin-Komplexe mit Bisphospbinoethan-Liganden / Hindered Ligand Motions in Transition Metal Complexes, XIX [I]. Octahedral Tungsten Olefin Complexes with Bisphosphinoethane Ligands

1983 ◽  
Vol 38 (8) ◽  
pp. 943-952 ◽  
Author(s):  
Cornelius G. Kreiter ◽  
Ulrich Koemm
Keyword(s):  
Nmr Spectroscopy ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Spectroscopic Behaviour ◽  
Ir And Nmr Spectroscopy

(OC-6-32)-W(CO)3[(CH3)2PC2H4P(CH3)2] (olefin) complexes (9-14) were prepared photochemically from W(CO)4[(CH3)2PC2H4P(CH3)2](l) via W(CO)3[(CH3)2PC2H4P(CH3)2]- (THF) (2) and the electron poor olefins dimethyl inalonate(3), fumarate (4), inothylfumarate (5), fluorofumarato (6), chlorofumarato (7) and bromofumarate (8). The stereoche­mistry of 9-14 was elucidated by IR and NMR spectroscopy. The hindered rotations of the olefin ligands in 9-14 were studied by D-NMR spectroscopy. 11-14 form two diastereomeric isomers when the olefin rotation is freezed. The spectroscopic behaviour of the dimethyl fumarato complex 10 gives unambiguous proof for the rotation of the olefin ligand around the metal-olefin-bond. Alternative motions are ruled out.

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