Related Experiment Video
Updated: Aug 14, 2026
Accessing Valuable Ligand Supports for Transition Metals: A Modified, Intermediate Scale Preparation of 1,2,3,4,5-Pentamethylcyclopentadiene
Published on: March 20, 2017
Solid-state 25Mg QCPMG NMR of bis(cyclopentadienyl)magnesium
1Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, Canada N9B 3P4.
Abstract:
Application of the "quadrupolar Carr-Purcell Meiboom-Gill" (QCPMG) sequence permits the first natural abundance solid-state 25Mg NMR study of an organometallic magnesium compound, bis(cyclopentadienyl)magnesium. Analytical and numerical simulations of both static and magic-angle spinning QCPMG NMR spectra beget an axially symmetric 25Mg electric field gradient (EFG) tensor (quadrupolar asymmetry parameter, eta(Q)=0.01(1)) with a nuclear quadrupole coupling constant of C(Q)=5.80(5)MHz. Restricted Hartree-Fock and hybrid density functional theory (B3LYP) calculations are in good agreement with experimental EFG values and predict a chemical shielding anisotropy of about 40-50 ppm, which we attempt to elucidate by numerical simulations. The parameters and orientation of the 25Mg EFG tensor are rationalized from examination of the crystal structure and molecular symmetry. The NMR properties of the cyclopentadienyl rings are examined by 13C[1H] CPMAS NMR, RHF and hybrid-DFT (B3LYP) calculations, and simulations of the effects of chemical exchange on the 13C powder pattern.
More Related Videos
06:53Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
04:51Synthesis of Triazole and Tetrazole-Functionalized Zr-Based Metal-Organic Frameworks Through Post-Synthetic Ligand Exchange
Published on: June 23, 2023
Related Concept Videos
02:42Valence Bond Theory
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
03:02Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
02:30Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
02:37Disubstituted Cyclohexanes: cis-trans Isomerism
In cyclohexane, the substituents can occupy different positions generating distinct isomers.
01:18Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group with both...