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Related Concept Videos

Spin–Spin Coupling: One-Bond Coupling01:17

Spin–Spin Coupling: One-Bond Coupling

Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...
Atomic Nuclei: Nuclear Spin State Population Distribution01:14

Atomic Nuclei: Nuclear Spin State Population Distribution

Near absolute zero temperatures, in the presence of a magnetic field, the majority of nuclei prefer the lower energy spin-up state to the higher energy spin-down state. As temperatures increase, the energy from thermal collisions distributes the spins more equally between the two states. The Boltzmann distribution equation gives the ratio of the number of spins predicted in the spin −½ (N−) and spin +½ (N+) states.
Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)01:20

Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)

Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
NMR Spectroscopy: Spin–Spin Coupling01:08

NMR Spectroscopy: Spin–Spin Coupling

The spin state of an NMR-active nucleus can have a slight effect on its immediate electronic environment. This effect propagates through the intervening bonds and affects the electronic environments of NMR-active nuclei up to three bonds away; occasionally, even farther. This phenomenon is called spin–spin coupling or J-coupling. Coupling interactions are mutual and result in small changes in the absorption frequencies of both nuclei involved. While nuclei of the same element are involved in...
Spin–Spin Coupling Constant: Overview01:08

Spin–Spin Coupling Constant: Overview

In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must have a...
¹H NMR: Interpreting Distorted and Overlapping Signals01:02

¹H NMR: Interpreting Distorted and Overlapping Signals

Spin systems where the difference in chemical shifts of the coupled nuclei is greater than ten times J are called first-order spin systems. These nuclei are weakly coupled, and their chemical shifts and coupling constant can generally be estimated from the well-separated signals in the spectrum.
As Δν decreases and the signals move closer, the doublets appear increasingly distorted. The intensities of the inner lines increase at the cost of those of the outer lines as the signals are slanted or...

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Updated: May 14, 2026

High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy
08:55

High-Temperature and High-Pressure In situ Magic Angle Spinning Nuclear Magnetic Resonance Spectroscopy

Published on: October 9, 2020

High-temperature spin crossover behavior in a nitrogen-rich Fe(III)-based system.

Cyril Cook1, Fatemah Habib, Tomoko Aharen

  • 1Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, ON, K1N6N5, Canada.

Inorganic Chemistry
|February 8, 2013
PubMed
Summary

A new iron(III) complex featuring a nitrogen-rich ligand exhibits spin crossover (SCO) behavior. This Fe(III) complex, bis(1H-tetrazol-5-yl)amine, demonstrates a high-temperature SCO transition, indicating potential for advanced material applications.

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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
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Spin Saturation Transfer Difference NMR (SSTD NMR): A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes
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Spin Saturation Transfer Difference NMR (SSTD NMR): A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

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Spin Saturation Transfer Difference NMR (SSTD NMR): A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes
11:44

Spin Saturation Transfer Difference NMR (SSTD NMR): A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

Published on: November 12, 2016

Area of Science:

  • Inorganic Chemistry
  • Materials Science
  • Coordination Chemistry

Background:

  • Nitrogen-rich ligands are crucial in designing functional coordination compounds.
  • Iron(III) complexes are known for diverse electronic and magnetic properties.
  • Spin Crossover (SCO) phenomena in metal complexes are of significant interest for molecular switches and sensors.

Purpose of the Study:

  • To synthesize and characterize a novel Fe(III) complex using a nitrogen-rich ligand.
  • To investigate the structural and magnetic properties of the new complex.
  • To determine if the Fe(III) center exhibits Spin Crossover behavior.

Main Methods:

  • Single crystal X-ray diffraction for structural elucidation.
  • Magnetic susceptibility measurements to probe magnetic behavior.
  • Synthesis and characterization of the Fe(III) complex using bis(1H-tetrazol-5-yl)amine (H(3)bta).

Main Results:

  • A new Fe(III) complex, Na(2)NH(4)[Fe(III)(Hbta)(3)]·3DMF·2H(2)O (1), was successfully isolated.
  • Structural analysis revealed an octahedral Fe(III) core coordinated by three Hbta(2-) ligands, forming a 2-D network linked by Na(+)/solvent chains.
  • Magnetic studies confirmed a high-temperature Spin Crossover (SCO) transition at T(1/2) = 460(10) K.

Conclusions:

  • The synthesized Fe(III) complex displays a unique 3-D network structure stabilized by hydrogen bonding.
  • The observed high-temperature SCO behavior in the Fe(III) center highlights its potential for applications in switchable materials.
  • This study contributes to the understanding of SCO phenomena in nitrogen-rich coordination complexes.